Though it’s not the central sorting facility it once was, the U.S. Post Office still operates a small window in downtown Brooklyn (271 Cadman Plaza) that will be open until 8 p.m. this Tuesday to accept your last-minute tax filings. The U.S. General Post Office was constructed in 1891 as both a federal courthouse and postal headquarters for the then independent city of Brooklyn. The architect, Mifflin E. Bell, designed the building in the prevalent Romanesque Revival style to have four courtrooms in addition to the main postal facilities.