TAMPA — The developers of a planned 52-story building downtown have closed on the site of Tampa's scuttled Trump Tower project, one of the city's last stretches of undeveloped waterfront.A joint venture of developer Larry Feldman's Feldman Equities and investment firm Tower Realty Partners paid $12.1 million for the 1.5-acre site in a deal that closed just before Thanksgiving. The project will cost just under $200 million, Feldman said.The high-rise, dubbed Riverwalk Tower, is envisioned as a mix of office space and upscale condos with shops, restaurants and a bar on the ground floor. Tampa's Riverwalk park runs along the property, now a weedy lot along the Hillsborough River at the corner of South Ashley Drive and Brorein Street.The developers' plans boast 203 high-end condos and 14 stories of offices featuring a rooftop garden, floor-to-ceiling windows with sweeping views and a lobby that opens onto the Riverwalk. The tower will be designed by Gensler, a global architecture firm with an office a block away.The building, which developers say would be the first new office building in Tampa in more than two decades, is scheduled to break ground in the second half of 2016 and open in 2018. It would be the tallest building in the region, developers say."We intend to build the best building ever built in the Tampa market, both on the office building portion and the residential portion," Feldman said. "It's our goal to provide an iconic building that's going to change the skyline of Tampa. Those are very lofty goals, I know, but that's the goal."The sale comes amid a building boom around downtown Tampa. The high-rise Skyhouse Channelside apartment building opened earlier this year, and more apartments are planned on the site of the Tampa Tribune and on South Morgan Street. Meantime, Tampa Bay Lightning owner Jeff Vinik has drawn up ambitious plans to revamp downtown that carry a $1 billion price tag.But none of those projects, Feldman said, include the same mix of luxury condos and office space that the Riverwalk Tower envisions. And none can match its height; condos will be on the 23rd floor and up, meaning they'll have better views than competing properties, he said.Of course, the tower isn't the first luxury office-and-condo project promised for the site. A decade ago, developers touted plans for the $300 million Trump Tower Tampa. Local businessmen drew up plans for another 52-story building, licensed Donald Trump's name and attracted hundreds of buyers for condos.RELATED: Buyers still feel burned by Donald Trump after Tampa condo tower failureBut the ambitious plans crumbled as builders found that the land would require a more expensive foundation and the real estate boom busted. By 2007, the local developers and Trump were in court, revealing that the real estate mogul's only investment in the project was his name and eventually killing the project.The property, which includes the CapTrust building on Ashley Drive, was foreclosed on and eventually sold in 2011 to Brownstone Tampa Partners for $5 million, less than half the $12.1 million they've now sold it for. The latest price is still below its peak in 2004, when the Trump Tower developers paid $16 million.Brownstone had considered developing the land itself, but recent valuations made the choice to sell "an easy decision," said Robert Owens, a developer who leads the Brownstone partnership."The market has definitely come back strong," even if prices haven't rebounded completely, Owens said. "It's a different set of economics."Reach Thad Moore at [email protected] Follow @ThadMoore.