A downtown block that’s been targeted for redevelopment for more than a decade may finally have found the right suitor.

Houston-based Patrinely Group is proposing a 32-story office tower on the east side of 15th Street between Welton and California, part of a two-phase development that could also include a large hotel.

The entire block, bounded by 15th, 16th, Welton and California streets, is controlled by local developer Evan Makovsky, who began painstakingly assembling all 11 parcels back in 2005 in hopes of seeing the long-neglected block restored to prominence.

“It is the right market, it’s the right time and it’s the right product,” Makovsky said this week.

“I don’t think I’ve really sat and pondered what it might be like when the construction starts,” he said. “I’ve thought more about when the total block is built out and a major hole in the donut hopefully gets filled in.”

The office portion of Block 162, as the project is being called, would feature 13 floors of parking — including three underground levels — and 21 stories of rentable office space in a modern, glass-heavy tower.

A tenant-only amenity area on the 12th floor would house a fitness center, meeting rooms, outdoor exercise area and indoor/outdoor social lounge with fire pits.

The name refers to the site’s block number on a 1859 survey map of East Denver.

“It’s a great site — it’s right on light rail, it’s adjacent to the 16th Street Mall, there are 20 hotels within walking distance,” Patrinely CEO Robert Fields said. “We think it’s the best site in the Central Business District, hands down.”

Patrinely has had concept meetings with the city, but no formal plans have been submitted, according to a city spokeswoman.

Only the office portion of the project is currently under review, although Fields said their hope is the office tower and hotel can be developed concurrently.

“We can certainly phase this thing — we’ve designed it in such a way so one project isn’t reliant on the other,” Fields said. “Our mission is to do both at the same time or see both done at the same time.”

A spokeswoman for Sage Hospitality — perhaps the most natural fit to operate the proposed hotel, given the fact its headquarters are on the same block — declined to comment.

Fields said Patrinely hopes to deliver the office tower as soon as the first or second quarter of 2019. That means construction would begin later this year or in early 2017.

The total cost of the project has not been disclosed. The office tower will be owned by the U.S. Office Development Program, a private equity fund co-sponsored by Patrinely and USAA Real Estate Company, a subsidiary of financial services company USAA.

“There are a lot of third-generation buildings on the market, a lot of outdated buildings on the market today that are full of tenants that are growing rapidly, with a new workforce that strongly desires being in a brand-new, efficient building with first-generation technology that’s state of the art,” Fields said. ”

There’s a lot of demand, based on the activity we’re seeing in the market, for that kind of building.”

Makovsky said plans for the block have always been mixed-use, with office, hotel, retail and potentially some residential.

Target in 2004 was circling the property for an urban store, but ultimately opted not to enter downtown Denver. The retail giant looked again in 2012.

All but two buildings on the block were demolished in 2007 to make way for redevelopment, which has been used in the years since for surface parking, an urban garden and a pop-up tent for events.

In 2008, Makovsky unveiled a complete exterior renovation to one of the remaining buildings, the historic Fontius building at 16th and Welton. After years of sitting all but abandoned, it’s now called the Sage Building after Sage Hospitality, its largest tenant.

But he Great Recession took its toll, and Makovsky and his partners mothballed the rest of the redevelopment for the better part of three years.

Makovsky said he recently decided to allow the hotel and office components to proceed separately, which paved the way for Patrinely’s proposal.

“The biggest problem was the timing, of construction, delivery and financing of the office building — the same issues on a hotel were not the same,” Makovsky said. “We just couldn’t get the timing together in a way that would bring it all to market.”

Any new development will have to integrate the other building on the block, the historic McClintock Building at 16th and California, which he acquired in 2008.

Makovsky, who has been in the downtown real estate business for more than 45 years, said Block 162 is “pretty much Main and Main when you talk about the 16th Street Mall.”

When he offered to redevelop the site a decade ago — earning the honorary title of “urban hero” from downtown advocates — it was an eyesore, home to several beat-up buildings and “some rough tenants” in the direct path between the city’s new 1,100-room Hyatt Regency Denver at Colorado Convention Center and the mall.

“I raised my hand and said I’ll try to do something about it. I’ll try to acquire it and do something that will be both economically feasible and good for our community,” Makovsky said.

“When you sometimes are driven a little bit more by a goal, if it takes longer, it takes longer,” he said. “You’re looking for the goal, not necessarily the gold.”

Emilie Rusch: 303-954-2457, erusch@denverpost.com or @emilierusch