Brentwood is a neighborhood in Northeast Washington, D.C., Bounded by Rhode Island Avenue NE, the train tracks of the Rhode Island Ave-Brentwood Metro station, Montana Avenue NE, and New York Avenue NE. And is named after the Brentwood Mansion built at Florida Avenue and 6th Street NE in 1817 by Robert Brent, the first mayor of Washington Cit…Brentwood is a neighborhood in Northeast Washington, D.C., Bounded by Rhode Island Avenue NE, the train tracks of the Rhode Island Ave-Brentwood Metro station, Montana Avenue NE, and New York Avenue NE. And is named after the Brentwood Mansion built at Florida Avenue and 6th Street NE in 1817 by Robert Brent, the first mayor of Washington City. He built it as a wedding present for his daughter Eleanor on her marriage as second wife to Congressman Joseph Pearson, and it stood for a hundred years before burning down in 1917.