Large, darkened retail spaces aren’t a good look for Atlanta’s signature street.

The next big void along the so-called Midtown Mile will be a large corner space that’s been home to Tex-Mex restaurant Mi Cocina for four years.

The Texas-based eatery suddenly closed Saturday, offering only this non-explanation on Facebook: "It is with a heavy heart that we close our restaurant here in Atlanta ... We have thoroughly enjoyed our time here and hope you will visit us in the Dallas/Fort Worth area," as What Now Atlanta (and before them, Tomorrow’s News Today) reports.

It’s the third major retail loss on Peachtree Street at the multi-block 12th & Midtown project in the last couple of years, following the closure of CB2 about a year ago and Republic of Couture fashion boutique in 2014. According to WNA, Mi Cocina spent about $1.5 million to build out its sprawling 8,800-square-foot space.

Add to that the empty buildings that once housed clubs Vanquish and Reign — vacant for almost two years now — and this key stretch of Peachtree Street is beginning to appear, as developers say, gap-toothed.

Midtown boosters have been trumpeting the Midtown Mile concept since 2005. The vision calls for a vibrant, 14-block corridor of shopping (a la Madison Avenue or Chicago’s Magnificent Mile) running up Peachtree from North Avenue to 15th Street. The concept’s momentum took a beating during the recession but showed signs of promise with the openings of STK, Cafe Intermezzo, and everything that’s since closed.

Daniel Corp., the developer behind 12th & Midtown, describes their project as the Midtown Mile’s “cornerstone.”

A jolt of life for the Midtown Mile could come in 2018, with the planned opening of Colony Square’s redo by North American Properties.

The redevelopment calls for transforming Colony Square’s bunker-like relationship with Peachtree into a more pedestrian-friendly experience (see below). So all the news isn’t necessarily grim.