Real World article
(written from a Production point of view)

Tal Shiar Headquarters were the headquarters of the Tal Shiar on Romulus, only mentioned in the the script of the Star Trek: Deep Space Nine episode "The Wire", and not the aired episode. In the script, Sisko wanted to go to the Tal Shiar headquerters after a member of the Federation Embassy named Stolpan was arrested by the Tal Shiar. Curzon Dax talked him out of it.