This post card, #36, was apparently one of a series of unknown numbers, printed as souvenirs of the Great San Francisco Fire and Earthquake of 1906.
The Obverse reads; "The silent sentinal among the ruins".
Marie Antonette Apartments on Van Ness afte the fire of April, 18,19,20 - '06. San Francisco.

The reverse bears a message.

ZFC Collectible Flag