Today , the Town of Potomac Historic District in Alexandria designates this historic portion of the city .
Today , the Town of Potomac Historic District in Alexandria includes 1,840 acres ( 7.4 km ) and 690 buildings .
Today , the Town of Potomac Historic District in Alexandria designates this historic portion of the city , and includes 1,840 acres ( 7.4 km ) and 690 buildings .