Built in 1439 (Ming Zhengtong era), Xuanwumen was the southwestern gate of Beijing's inner city wall. The wall and gate-tower were demolished in the 1960s; today only the metro station name preserves it. 宣武 means 'proclaim military might' - paired with eastern gate 崇文门 ('revere learning').
NOTE: The famous 626 CE coup where Tang prince Li Shimin killed his brothers and seized the throne is 玄武门之变 (Xuán-wǔmén, 'Black Tortoise Gate'), not Beijing's 宣武门. The two gates are commonly confused but unrelated.
