Founder Ariana Austin brought Nuit Blanche from Paris to DC. Art All Night is an all-night festival celebrating contemporary art throughout DC's neighborhoods. Stops include Dupont Circle, Shaw, North Capitol, H Street (NE), and Congress Heights. Art All Night is meant as a celebratory interruption in the truest sense of art in public spaces.
If you're lucky enough to be in town during mid-September, this one-night-a-year experience is an absolute must. Visual, music, media, performance, spoken word, and graffiti artists participate in this city-wide, DC arts commission. Even if you're not trying to experience Art All Night, if you're in town, you won't be able to avoid it.
Each neighborhood has its own arts vibe, so look at the schedule. (Dupont has mostly visual art as that's where the galleries are, for example).