This hallway has been improved by new lights and flooring, but much more is in store at the plaza. (Evy Mages/For Capital Business)

Not too long ago, entering the retail corridor of L’Enfant Plaza was a journey into a dark, cavernous labyrinth, where, judging by the dated brass fixtures and vanity lighting, time seemed to have stop in 1988. Vacant storefronts peppered the halls. CVS was the closest thing to a brand-name boutique. And your best bet for lunch was McDonald’s.

Not anymore.

Fast-casual eateries Roti Mediterranean Grill, Potbelly and Au Bon Pain opened earlier this summer and now line the luminous east wing of the promenade, bathed in sunlight from the floor-to-ceiling windows. Red banners on temporary drywall herald the coming of five more restaurants, including Five Guys and Moe’s Southwest Grill, before the end of the summer.

And that’s just the beginning of a transformation JBG Cos. says will usher in a new era for its sprawling District complex. The Chevy Chase developer is pouring $40 million into the long-forgotten underground mall, overhauling every drab corner of the 180,000-square-foot space.

“It’s very heavy architecture,” said Britt Snider, JBG development officer. “We’re trying to lighten it up so it doesn’t feel so intimidating.”

This pyramid in the mall’s courtyard will be replaced with a two-story glass atrium. (Evy Mages/For Capital Business)

Architecture firm SmithGroup is revamping the space with modern birch accents, recess lighting and a red, white and gray color palette, carried throughout the decor and flooring.

The retail redevelopment is part of a larger renovation and expansion effort taking place at the complex, composed of a 372-room hotel and two office buildings in Southwest Washington. Plans call for a 234-room Homewood Suites, 500,000 square feet of more office space and, among other things, a make-over for the existing hotel rooms.

JBG’s effort to revitalize the canyon of concrete buildings is occurring amid a much-needed rebirth of Southwest Washington, where at least five projects are in some stage of development.

Forest City, for instance, has delivered some 140,000 square feet of retail in the past year, including fine dining restaurant Station 4, as a part of its Waterfront Station development. PN Hoffman and Madison Marquette, meanwhile, are gearing up to break ground late next year on the Wharf, a public-private venture that promises hotels, restaurants, shops and apartments.

This collection of lifestyle projects aims to breath new life into an area that has long suffered from a paucity of convenient amenities. What little that has existed centered on the 9-to-5 office crowd, especially at L’Enfant Plaza.

Snider said the company took the paltry after-hours options into consideration in planning the second phase of the retail redevelopment. Casual dining restaurants are envisioned for the west wing of the retail promenade, where demolition is underway with completion slated for early 2013.

“The true test of this transformation will be whether we see people after work or on the weekends,” Snider said.

As much as JBG wants to create a vibrant late-night atmosphere, he said the company is keen on catering to the needs of the daytime population — more than 28,000 workers are within a half-mile of the complex. A smattering of business-wear boutiques will be sprinkled along the corridor off the food court, while a daycare and gym are being considered.

“We’ve seen a lot of interest in lease renewals from our existing office tenants because they know the retail is coming and they’re now starting to see it,” Snider said.

The renovation, he added, is also attracting former retail tenants that vacated the mall over the past decade. They will have to cough up a bit more money than before, as average rents fall in the $40-per-square-foot range, double what they were several years ago.

Snider admits the change in pricing may be prohibitive for mom-and-pop shops, but he said JBG had to justify the cost of construction. There are still small businesses signing up for space. District-based FYI: Frozen Yogurt Indulgence, slated to debut this month, was drawn by the location and promising sales projections, said Managing Partner Ash Rahimi. Snider noted that Roti and Potbelly are reporting $5,000 a day in sales.

When JBG purchased L’Enfant Plaza in 2003, nearly 40 percent of the retail space was empty. The company had set out to give the space a face lift, but stalled once the economy faltered.

The last major renovation of the 40-year-old complex took place in 1999, when Dutch pension fund Sarakreek Holdings replaced the courtyard fountain with a pyramid-shaped skylight above the underground retail.

To add more natural light and depth, JBG plans to replace the entire courtyard with a glass atrium, rising two stories above ground. It will serve as a new entry to the retail corridor, which at full build-out will top 205,000 square feet.

Neighborhood commissioner Bob Craycraft is “excited JBG is opening up the retail space,” but bemoans the “lack of connectivity” between the plaza and residential communities to the south. The Southwest Ecodistrict Initiative, a planning group to which Craycraft and JBG belong, is reviewing several options for improving pedestrian access along 10th Street and the Ninth Street Bridge.

The isolation of the plaza may also ward off weekend crowds that can easily head to Waterfront Station of the Wharf, once it comes into play, said retail broker John Asadoorian. “Those projects have a greater chance of become destinations” because of their layout, he said. Still, L’Enfant can play to its strengths by “creating a quality of life for the office tenants with best-in-class food.”