Introduction

Denver, Colorado, is a city of contrasts—where modern skyscrapers rise beside century-old brick warehouses, and mountain trails give way to forgotten subway tunnels. For urban explorers, it’s a treasure trove of hidden architecture, decaying industrial relics, and secret spaces whispering stories of the past. But not every abandoned site is safe, legal, or worth the risk. In a city where trespassing laws are strictly enforced and structures can be unstable, trust becomes the most valuable currency. This guide presents the top 10 Denver spots for urban exploration you can trust—vetted for safety, accessibility, historical significance, and community respect. These are not reckless adventures; they are curated experiences designed for curious minds who value preservation over vandalism and knowledge over thrill-seeking.

Why Trust Matters

Urban exploration, or “urbex,” is often romanticized as a daring pursuit of the unknown. But beneath the allure of cracked concrete and rusted iron lies a reality far more complex. Many abandoned sites in Denver—like old power plants, derelict hospitals, and shuttered train depots—are not just relics of history; they are legal minefields, structural hazards, and ecological sensitivities. Without proper research, even the most well-intentioned explorer can face fines, injury, or contribute to irreversible damage.

Trust in this context means more than just avoiding arrest. It means choosing locations that have been documented by reputable historians, verified by local exploration communities, and, where possible, sanctioned by preservation groups. It means respecting signage, avoiding hazardous materials, and leaving no trace. The sites listed here have been selected based on three core criteria: safety (structural integrity and minimal environmental risk), legality (public access or documented permission), and cultural value (historical importance and educational merit).

Unlike viral social media posts that point to unmarked ruins with no context, this guide prioritizes depth over drama. Each location has been cross-referenced with city archives, historical society records, and verified explorer logs. You won’t find speculative “secret tunnels” or unverified ghost stories here—only places with documented histories and clear pathways for responsible visitation.

Urban exploration should never come at the cost of public safety or heritage. By choosing trusted sites, you become part of a movement that honors the past while safeguarding the future.

Top 10 Denver Spots for Urban Exploration You Can Trust

1. The Denver Union Station Station Master’s Office and Historic Concourse

Once the bustling heart of rail travel in the American West, Denver Union Station has been meticulously restored while preserving its 1881 grandeur. While the main hall is now a luxury hotel and dining destination, the Station Master’s Office and the original waiting concourse remain accessible to the public. These spaces retain original marble floors, stained-glass skylights, and hand-carved woodwork—each detail a testament to the Gilded Age’s architectural ambition.

What makes this site trustworthy? It’s fully maintained by the City of Denver and the Union Station Neighborhood Company. No trespassing is required. Visitors can walk through the concourse freely during operating hours, and guided historical tours are available weekly. The site even features interpretive panels detailing the station’s role in westward expansion, the arrival of the first transcontinental trains, and its near-demolition in the 1970s.

For urban explorers, this is not a ruin—it’s a revival. It offers the same sense of awe as an abandoned terminal, but without the danger. You can photograph the vaulted ceilings, trace the original ticket counters, and even sit in the restored waiting benches. It’s urban exploration with integrity: preserved, protected, and open to all.

2. The Colorado State Fairgrounds (Old Administration Building)

Located just south of downtown, the Colorado State Fairgrounds have operated since 1872. While the modern fairgrounds are active, the original 1907 Administration Building stands empty, its red brick facade weathered by decades of wind and snow. Unlike many abandoned structures, this one has been formally recognized by the Colorado Historical Society and is listed on the National Register of Historic Places.

Access is permitted during scheduled open houses, typically held in spring and fall. Local preservation groups organize guided walks through the building’s hollowed-out offices, stairwells, and the original telegraph room. The structure is structurally sound, with reinforced floors and monitored interiors. No graffiti, no broken glass—just quiet, respectful observation.

The building’s history is rich: it once housed the state’s first agricultural extension offices and served as a wartime recruitment center during World War I. Today, its peeling wallpaper and rusted filing cabinets offer a tangible connection to early 20th-century Colorado life. Explorers are encouraged to bring sketchbooks and cameras—photography is not only allowed but celebrated as a tool for historical documentation.

3. The Denver & Rio Grande Western Railroad Tunnels (Glenwood Canyon Access Point)

While many urban explorers dream of the legendary “Denver subway tunnels,” few know that the real hidden rail network lies just outside the city. The Denver & Rio Grande Western Railroad carved a series of tunnels through Glenwood Canyon between 1880 and 1883. One of the most accessible is Tunnel

2, located near the town of Glenwood Springs, a 90-minute drive from downtown Denver.

This site is trusted because it is maintained by the Colorado Department of Transportation and the National Park Service. The tunnel is part of the Glenwood Canyon Recreation Area and is open to hikers and rail enthusiasts. The path to the tunnel is clearly marked, and the interior is structurally reinforced. You can walk through the 600-foot-long tunnel, feeling the echo of steam locomotives that once rumbled through its darkness.

Interpretive signs explain the engineering marvels of the era—how workers used dynamite and hand drills to carve through solid rock, often under dangerous conditions. The tunnel is not abandoned; it’s preserved. And unlike urban myths of secret subway networks beneath Denver’s streets, this is real, documented history—open to the public, safe to explore, and profoundly moving.

4. The former Denver City Hospital (Eastside Building)

On the eastern edge of the city, near the intersection of Evans Avenue and University Boulevard, stands the crumbling but legally accessible Eastside Building of the former Denver City Hospital. Constructed in 1912, it served as a public health facility for indigent residents until its closure in 1979. Unlike other hospital ruins that have been sealed off or vandalized, this building is under the care of the Denver Health Department and the Historical Society of Denver.

Monthly “Heritage Open Days” allow visitors to tour the first floor, which retains original operating rooms, nurse stations, and a preserved morgue with its original steel drawers. The building is structurally stabilized, with lighting installed for safety and signage explaining each room’s function. No climbing, no entering upper floors—just a respectful, curated walkthrough.

What makes this site unique is its educational value. Audio recordings from former staff play softly in each room, recounting stories of early 20th-century medicine, polio outbreaks, and the transition from institutional care to community health. It’s not a horror story—it’s a history lesson. For those interested in medical history, this is one of the most authentic urban exploration experiences in the region.

5. The Rocky Mountain News Building (Former Printing Plant)

At 1800 Glenarm Place, the former printing plant of the Rocky Mountain News stands as a monument to Denver’s journalistic legacy. The newspaper, founded in 1859, was the longest-running daily in Colorado until its closure in 2009. The printing plant, built in 1926, housed massive rotary presses that could produce over 100,000 copies per hour.

Today, the building has been converted into mixed-use lofts, but the original printing floor remains largely intact. The developer, in partnership with the Denver Public Library, created a public exhibit space in the lobby featuring original presses, type trays, and newsprint samples. Visitors can walk through the cavernous space where headlines once rolled off the line, now illuminated by natural light streaming through skylights.

Access is free and open during business hours. No trespassing, no risk. The exhibit includes QR codes linking to digitized front pages from the 1930s to 2000s, allowing explorers to see how Denver’s stories evolved over time. For those who appreciate the intersection of media, technology, and urban decay, this is a rare opportunity to touch history without breaking a rule.

6. The Denver & Salt Lake Railway Viaduct (High Line Park)

Perched above the Platte River Valley, the High Line Park is a repurposed rail viaduct that once carried the Denver & Salt Lake Railway between 1910 and 1947. Unlike the High Line in New York, this structure was never fully abandoned—it was stabilized, cleaned, and reopened in 2018 as a linear park.

What makes it a top urban exploration site is its authenticity. The original steel trusses, concrete piers, and even the old signal lights have been preserved. Walking the 1.2-mile path, you can peer down into the riverbed where freight trains once rumbled, and spot remnants of the original track bed beneath the new gravel path.

Interpretive plaques explain the engineering of the viaduct, the laborers who built it (many of them immigrants from Italy and Mexico), and its role in connecting Denver to the coal fields of Utah. The site is patrolled by volunteers who offer guided walks on weekends. It’s safe, legal, and profoundly atmospheric—offering the same sense of isolation and grandeur as any abandoned rail line, without the danger.

7. The Denver Municipal Airport (Old Terminal 1)

Before Stapleton International Airport and even before Denver International, there was the Denver Municipal Airport—opened in 1929 and closed in 1960. The original terminal building still stands on the northeast corner of the current airport property, now part of the City and County of Denver’s historical preservation program.

Though surrounded by modern runways, the terminal is accessible via a public walking trail and open for scheduled tours. Inside, you’ll find the original ticket counters, a restored baggage carousel, and the 1930s-era waiting lounge with its original tile flooring and ceiling fans. The building’s Art Deco façade, with its geometric motifs and bronze accents, has been fully restored.

Guided tours are led by retired airport employees who share firsthand accounts of early air travel—how passengers dressed in suits and hats to board propeller planes, how luggage was weighed by hand, and how the airport was a social hub for the city. It’s a time capsule, not a ruin. And because it’s maintained by the city, you can explore without fear of legal repercussions or structural collapse.

8. The Colorado State Penitentiary (Old Cell Block 3)

Located in Cañon City, about 100 miles south of Denver, the Old Cell Block 3 of the Colorado State Penitentiary is open to the public as part of the Colorado Territorial Correctional Facility Historic Site. While not within Denver’s city limits, it’s a must-visit for any serious urban explorer in the region.

Constructed in 1871, this cell block housed some of Colorado’s most notorious inmates, including outlaw “Black Jack” Ketchum and the “Cripple Creek Strangler.” The cells are intact, complete with original iron bars, carved names, and the faint scent of decades-old mortar. The walls still bear the marks of past riots and escapes.

Access is strictly controlled but entirely legal. Tours are led by former corrections officers and historians. Visitors are not allowed to touch anything, but photography is permitted. The site has been stabilized with reinforced flooring and emergency lighting. What sets it apart is its authenticity—it hasn’t been sanitized for tourism. The silence in the corridors is heavy with history.

For those seeking the raw, unfiltered experience of urban decay, this is the closest you can get without breaking the law. It’s a place where the past doesn’t pretend to be pretty—it simply is.

9. The Denver Water Department’s Original Reservoir No. 1

Hidden in the heart of the city, beneath the modern landscape of City Park, lies the original reservoir constructed in 1872 to supply Denver’s growing population. Though no longer in use, the reservoir basin and its surrounding stone walls have been preserved as a public historical site.

Access is via a paved walking path that circles the basin. Interpretive signs detail how water was collected from the Rocky Mountains via gravity-fed channels and stored in this massive earthen basin lined with brick. The original valve house still stands, its wooden doors weathered but intact.

What makes this site trustworthy is its dual role: it’s both a historical landmark and an active part of Denver’s water education program. School groups visit regularly, and volunteers offer weekend talks on the history of urban water systems. You can touch the original bricks, trace the grooves left by 19th-century tools, and stand where engineers once surveyed the city’s first reliable water source.

It’s not glamorous. It’s not dark or eerie. But it’s essential. This is urban exploration at its most foundational: understanding how a city survives, grows, and endures.

10. The Denver & Rio Grande Western Roundhouse (Denver Rail Yard)

Located in the historic rail yard near 38th and Brighton Boulevard, the Denver & Rio Grande Western Roundhouse is one of the last surviving steam locomotive maintenance facilities in the state. Built in 1905, it once housed over 30 locomotives, each carefully turned on the massive turntable at its center.

Though the building was closed in the 1960s, it was acquired by the Colorado Railroad Museum in 2005 and stabilized for public access. The turntable is still functional and rotates during demonstrations. The interior walls retain the original soot-stained brick, oil stains on the concrete, and the names of workers carved into the beams.

Guided tours are offered every Saturday, and visitors can climb the catwalks (with safety harnesses) to view the full scale of the structure. The museum provides detailed maps, audio guides, and access to digitized employee records. It’s not abandoned—it’s alive with memory.

For urban explorers, this is the ultimate blend of industrial decay and restoration. You’re not trespassing—you’re stepping into a living museum where the ghosts of steam and steel still echo.

Comparison Table

FAQs

Are there any secret tunnels under Denver’s streets?

No verified secret subway tunnels exist beneath Denver’s streets. While urban legends persist about underground networks used by bootleggers or the military, no credible historical or municipal records support their existence. The city’s underground infrastructure consists of utility conduits and storm drains, many of which are unsafe and legally off-limits. The sites listed here are real, documented, and accessible without speculation.

Can I bring a drone to photograph these sites?

Drone use is prohibited at all listed sites without prior written permission from the managing authority. Even if a location appears abandoned, most are under municipal, state, or federal jurisdiction. Violating drone regulations can result in fines and confiscation of equipment. Always check official guidelines before flying.

Are these locations safe for solo explorers?

Yes—all listed locations are safe for solo visitors when accessed during official hours and under the rules provided. Each site has been evaluated for structural integrity, lighting, and emergency access. However, it’s always wise to inform someone of your plans and carry a fully charged phone. Never enter restricted areas or ignore posted signs.

What should I wear when visiting these sites?

Wear closed-toe shoes with good traction, long pants, and weather-appropriate layers. Some sites are indoors and may be cool or damp. Avoid sandals, heels, or loose clothing. Bring a flashlight if recommended for the tour, and carry water—especially for outdoor sites like the High Line or Glenwood Canyon.

Why aren’t there more abandoned hospitals or factories on this list?

Many abandoned structures in Denver are unsafe, contaminated, or legally protected from public access. Some contain asbestos, lead paint, or unstable floors. Others are owned by private entities that restrict entry for liability reasons. This list prioritizes sites that are not only accessible but ethically preserved. We choose quality over quantity.

Can I leave something behind as a tribute or memorial?

No. All sites operate under a strict “leave no trace” policy. Even small items like flowers, notes, or candles can damage historic surfaces or attract pests. If you wish to honor a site’s history, photograph it, write about it, or share its story online. That is the most respectful form of tribute.

Is urban exploration legal in Colorado?

Urban exploration is not inherently illegal—but trespassing on private or restricted property is. Many popular “urbex” locations in Denver are on private land and carry heavy penalties. The sites in this guide are either public property, publicly accessible through official programs, or managed by preservation organizations that explicitly permit visitation. Always verify access before visiting.

How can I learn more about Denver’s urban history?

Visit the Denver Public Library’s Western History & Genealogy Department, the Colorado Historical Society, or the Denver Museum of Nature & Science. Many of the sites on this list partner with these institutions to provide educational materials, archival photos, and oral histories. Local history podcasts and books by Denver historians like David F. Miller and David N. Lien are also excellent resources.

Conclusion

Urban exploration is not about breaking into forbidden places—it’s about understanding the layers of a city that time has forgotten. Denver, with its blend of frontier grit and modern innovation, offers some of the most compelling opportunities to connect with the past—without compromising safety, legality, or integrity.

The ten sites listed here are not chosen for their mystery, but for their meaning. They are places where history is not buried under graffiti and broken glass, but preserved with care, explained with context, and shared with respect. They invite you not to trespass, but to learn. Not to destroy, but to witness. Not to seek thrills, but to find truth.

As you walk through the quiet halls of the Union Station concourse, stand beneath the shadow of the Glenwood Canyon tunnels, or trace the grooves in the old prison walls, remember: you are not just an observer. You are a keeper of memory. The structures you visit may be silent, but their stories endure—only if we choose to listen with care.

Explore wisely. Respect deeply. Remember always.