Shadow Room on K Street is celebrating its third anniversary tonight. (Michael Temchine for The Washington Post)

This weekend finds two very different bars celebrating their birthdays, but both are doing it in characteristic style: Shadow Room is throwing open the doors — and the bar — for a late-night affair, while Mad Fox Brewing Company is tapping three special beers and giving away pint glasses.

For three years, Shadow Room has been a destination for everyone from George Washington University students to Washington Wizards players to DJ Pauly D. The upscale nightspot sports plenty of futuristic touches — you can order a drink with an iPhone! — but it’s the DJs and the bottle service that keeps crowds coming back. For tonight’s party, RSVP on for free admission to Blush Fridays, show up early for an open bar from 9 to 11, and dance all night to DJ Vicious’ mix of house and Top 40.

Saturday in Falls Church, Mad Fox Brewing Company marks its first year in business with a daylong open house. Beers will be flowing all day: At noon, Brewer Bill Madden will tap the Oaked Slobberknocker American-style Barleywine — a strong beer aged in oak Catoctin Creeek whiskey barrels — and follow it up at 3 p.m. by unveiling a similarly aged version of his malty, sweet Wee Heavy Scottish Ale. Also beginning at 3 p.m.: Everyone who purchases a beer takes home a special anniversary pint glass.

At 8 p.m. Madden will offer the first taste of a work-in-progress beer called Black 100: a strong black ale that’s been aging in bourbon barrels but isn’t quite finished yet. While you sip, the Levi Stephens band plays from 9 p.m. to close.

There’s a special food menu for the anniversary — check it out on the Mad Fox Web site — and beers available on cask as well as draft. Admission is free.