The development team seeking to build the would-be tallest building in Denver filed a site concept with the city last week calling for an 81-story, mixed-use tower at the southeast corner of 17th and California streets downtown.

City staffers say the filing, first reported by Colorado Public Radio’s Ryan Warner on Saturday, was received on or about Feb. 14. The concept, which officials say is the earliest step in the city’s site plan review process and subject to change, outlines plans for a tower 25 stories taller than the 56-story Republic Plaza building, Denver’s loftiest structure to date. The new skyscraper would contain a hotel, residential units and retail space, according to a developer description city officials shared with The Denver Post on Sunday.

“A residential lobby, hotel lobby and a proposed restaurant/bar will occupy and engage the first two levels activating the street,” developers wrote. ” At the time of this concept submittal there are planned to be 780 parking spaces within the structure.”

The submission comes approximately five months after Michael Ursini, the co-founder and managing partner of New York-based developer Greenwich Realty Capital, said a project that would build Denver’s tallest building at that corner was “100 percent going forward,” despite no plans for it being in the city’s planning pipeline at the time. When Greenwich released a site concept in September, the building — dubbed Six Fifty 17 — was projected to be 90 stories and 1,000 feet tall, both figures that would make it far taller than any existing skyscraper in Colorado. Greenwich included a disclaimer then that all aspects of its plans were subject to change. The portion of the site concept shared with the Post on Sunday did not mention a projected height in feet.

New York City-based Crown Architecture and Consulting is the executive architect and development manager for the project. Michael Santora, the firm’s principal, relayed via email Monday that Greenwich Realty Capital leaders are “excited to part of Denver’s vibrant growth and pleased that the project is progressing.”

Greenwich has decided not to make further comments about the building at this time, Santora said.

Further information about the concept is unlikely to be available through the city until Tuesday. Denver’s municipal offices are closed Monday for Presidents Day.

Updated Feb. 19, 2018, at 3:40 p.m. This story was updated to include information from Crown Architecture and Consulting shared on behalf of developer Greenwich Realty Capital.