This is a former church that has been converted to an arts space,
Blind Whino. They have events occasionally throughout the year that are open to the public. The inside of the church, although a bit dated perhaps, has some great murals. There is a concert venue on the second floor and and a dance floor space and a stage on the first floor, with additional space for art shows. There was one party that my friends and I attended last October there that had a great blues band and an open bar with plentiful whiskey!
Also, I am glad you got to see Greenleaf... this is off the usual DC tourist area...