Built in 1848 as Brooklyn's City Hall, this Greek Revival landmark is one of Brooklyn's handsomest buildings. Adorned with Tuckahoe marble, it features a hammered square rotunda and a two-story Beaux-Arts courtroom. Today the building serves as the office of Brooklyn's borough president and the home of the Brooklyn Tourism & Visitors Center (718/802–3846 www.visitbrooklyn.org), which has historical exhibits, a gift shop, and helpful information. It's open weekdays 10–6. Each Tuesday and Saturday, as well as Thursday from April through December, a greenmarket sets up on the flagstone plaza in front.