The third and largest building in the 20 Midtown development got final approvals to start construction Wednesday morning.

The third building will take up a full city block and have 246 apartments. Scott Bryant of Scott M. Bryant & Co. and Dick Schmalz of RGS Properties are developing the Publix-anchored project.

The third building will feature an amenity deck on the fourth floor which will have a 25-by-85-foot pool, a putting green, several gas grills, bocce ball, a putting green, and a fitness center that's both indoors and outdoors.

"The fourth floor amenity deck is going to be really, really special," Schmalz said. "The few potential residents we've shown it to have said, 'Gosh, this isn't an apartment complex. This is a country club.'"

The first floor will have about 40,000 square feet of first floor retail space. Schmalz said he isn't ready to announce tenants yet, but he said he has gotten some interest from both retailers and companies looking for office space, so there might be some of that.

The Birmingham Design Review Committee approved the plans for the new construction. The site has already been demolished, and the developers have done environmental cleanup and utility relocation work. Schmalz said the team plans to start foundation in 30 to 45 days.

Schmalz said his team estimates the first retailers to open by the end of 2018 with apartments hopefully opening within the first quarter of 2019.

Tammy Cohen of Cohen Carnaggio Reynolds is the architect. Martin Smith of SRS Real Estate Partners is managing leasing the retail space.

The project, on three blocks at the intersection of Third Avenue South and 20th Street South, has three phases: the first is anchored by Starbucks, and other tenants include Chipotle Mexican Grill and AT&T. It's got 36 apartments over it, mostly 1-bedrooms with a few studio units. The second phase is anchored by the Publix and has 75 apartments above it. The developers had bought the neighboring Liberty National building out of foreclosure, but the deal fell through when it was redeemed.