Historic Cathedral High School building in Denver sees "significant deterioration" from urban explorers, vandals

By CBS Photojournalist Eric Blumer

A historic building at 1840 Grant Street sits dilapidated on the east side of Denver's skyline. The 104-year-old Spanish Renaissance-style old Cathedral High School has been overrun by vandals, unhoused drug addicts and "urban explorers." A push is now on to preserve it.

The nonprofit urban preservation organization Historic Denver is leading the charge.

"Leaving a building like this can be a pathway towards demolition by neglect, and it would be a travesty if it was to be allowed to be demolished through lack of upkeep," said John Deffenbaugh, Historic Denver's CEO.

Cathedral High School was built in 1921 by the Catholic Diocese.

"There really is no other building in Denver quite like this," Deffenbaugh said.

It was hailed as "magnificent" and "one of the most beautiful pieces of architecture in America." It's been a high school, a convent, a crisis support center for those affected by the AIDS epidemic, and most recently artist studios. At one point it was renamed the Seton House.

Today, it has become an eyesore and a danger.

"Unfortunately, the owner is not securing the buildings," Deffenbaugh said. "People are living in this structure. The windows are not boarded up, and it's causing significant deterioration."

Urban explorers are those who seek and enter abandoned structures. They ignore the "no trespassing" signs. Once inside, they often photograph or shoot video of their adventures and then post them online for the public to see. Cathedral High has become a popular destination. Anonymous urban explorers told CBS Colorado many find easy entry. 

"Probably like 50 people a day to be honest," the anonymous urban explorer said. "Somebody posted on TikTok and it went pretty viral, because it's so easy to get into. I've probably been in here about three times. We just explore and take pictures. There's a bunch of people who come here to destroy stuff, though."

 "The inside now is destroyed, like, every single wall has holes in it, there is trash all over the floor, they started tagging on the walls, started destroying the windows, it got bad."

Deffenbaugh says Historic Denver is asking city leaders to "implement the maximum fine possible to ensure this unique building exists into the future."

In 2011, the building was slated for demolition but Historic Denver and other preservation groups fought to save it. Five years later, it was sold to a New York City Developer, RAFMO, LLC, affiliated with GFI Capital Resources Group, that planned to create a vibrant hotel with retail and office space. But the project stalled. The developer says they were plagued first by a slow permitting process and then the COVID-19 pandemic and now high interest rates. Cathedral High sat vacant, was inspected, and was put on the city's Neglected and Derelict Buildings list.

Denver Police and Fire responded to numerous calls, but they stopped, telling the Department of Community Planning and Development it was "too dangerous."

The owner boarded up some windows and doors, but vandals quickly tore them down. Private part-time security was hired, but the owner insists their ability to prevent trespassing is limited.

Then in August 2025, after a hearing, an administrative judge levied a fine against the owner for $139,500 -- $500 a day for each day noncompliant between October of 2024 and July of 2025. That fine was set to increase to $999 a day after Oct. 9. The owner has responded with their own lawsuit claiming the fine is "grossly disproportionate and excessive."

"Denver has a neglected and derelict buildings ordinance which exists for precisely buildings like this to ensure that they're preserved and they can stick around long enough so they can be meaningfully reused in the future," Deffenbaugh said. "I'm full of hope for this building. It's perfectly salvageable, it's stunningly beautiful, and it's much loved by its local neighbors. If we just allow it to go to ruin, what does that say about us? And if you think it's an inevitability that this building's going to be demolished, then that's an indictment on us all."

Historic Denver shared the following "timeline of Cathedral High School / Seton House":

1921 - Built as Cathedral High School, designed by architect Harry J. Manning.
Mid-20th Century - Expanded to include a convent; later transitioned into Seton House.
1980s-1990s - Served as a crisis shelter during the AIDS epidemic, youth programs, and later artist studios.
2011 - Facing demolition threat; Historic Denver, CHUN, and CPI successfully opposed.
2016 - Purchased by GFI Development, with plans for adaptive reuse as a hotel.
2021 - Rehabilitation announced but never moved forward.
2025 - Property cited as Neglected and Derelict by the City of Denver; Show Cause Hearing held July 24.
August 2025 - Judge issues ruling: $500/day fines retroactive to October 2024 ($139,500 total), escalating to $999/day if not in compliance by October 9, 2025.

The group 1840 Grant LLC released the following statement about the building.

"When 1840 Grant LLC acquired the property in 2016, our vision was to create a vibrant, adaptive reuse project that would bring new life to the site through a mix of hotel, retail, and shared office space. We sought input from many local stakeholders, including Historic Denver, local residents and businesses. It was a very exciting and collaborative effort. We invested significant time and resources in preparing plans, securing financing, and positioning the project for completion by 2021. Unfortunately, because of the level of construction activity happening in Denver, securing approvals from the Denver Community Development Department took us into late 2019. These delays, coupled with the unprecedented challenges of the COVID19 pandemic, especially for hospitality, made it impossible to obtain financing and move the redevelopment forward as originally intended. We have since tried to restart the project but the current challenges in the capital markets caused by high interest rates impact projects for most uses, including hospitality and multifamily. Regarding vandalism, while we have engaged private security, their ability to prevent trespassing is limited. This remains an ongoing challenge not just for our property, but for many sites across central Denver that continue to be impacted by criminal trespass and vandalism. We are committed to the long-term success of this property and look forward to working closely with the new city administration to identify solutions that protect the site from perpetrators of vandalism and ultimately allow for the redevelopment of property to its full potential. We have worked collaboratively with local stakeholders in the past and will continue to do so."