Did the 814th General Hospital have a physical address or was it an administrative designation?
Yes, the 814th Hospital Center had physical addresses in Paris,
beginning in January, 1945.
Initially, a 5-story stone building at 43, rue de Villiers, on the outskirts of Paris, was requisitioned for Center headquarters. Two floors were reserved for the French families already living there, and the Center used the remaining space.
Late in March, 1945, the Center obtained an existing Paris residence at 42, Boulevard Victor-Hugo, for its administrative functions.
Some administrative personnel and Junior Officers were quartered in these locations, but Senior Officers were billeted in Paris hotels.