The London-themed Underground at St. Arnold's will close in late July and reopen with a Belgian theme as St. Arnold's the Abbey in August . (Alex Baldinger/The Washington Post)

It’s the end of the line for the Underground at St. Arnold’s Cleveland Park. The London-themed basement bar and sibling of the six-month-old mussel bar upstairs will be closing in late July or early August.

But the space isn’t going out of service for very long, said St. Arnold’s operating partner Mark Moore: By Aug. 15, the digs will reopen as St. Arnold’s the Abbey, with a Belgian theme replacing the British.

“We just kind of paid lip service to this while we got our product going,” Moore said of the outgoing British decor. With two St. Arnold’s up and running (the Jefferson Place location, near Dupont Circle, opened in late 2010), the plan is to continue the emphasis on Belgian fare.

The primary focus, as one might presume for a place named for the Flanders-born patron saint of hop-pickers, will be on Belgian beers. Moore plans to spotlight beers certified by the Belgian Family Brewers — think Bavik, Duvel and De Konnick — which guarantees their independent, family-run Belgian origin; don’t expect to find any InBev beers, like Stella Artois or Hoegaarden, Moore said.

The British pub fare will be replaced by the St. Arnold’s menu of mussels, frites and sandwiches, Moore said, except for the Underground’s selection of hot dogs, which are staying.

To furnish the abbey theme, Moore plans to replace the room’s existing tables and chairs with church pews — he has a supplier for those, believe it or not — which will provide enough seating for 55 to 60 guests. But unlike most cloistered monasteries, this one will have plenty of flat-screens.

“It’s still America,” Moore said. “There’s going to be football.”