Scuola Grande di San Marco, Great Hall for assemblies (Salone delle adunanze, also called the Chapel) now part of the Ospedale Civile Santi Giovanni e Paolo, Castello.
The altar is the work of Sansovino. The paintings on the wall are the work of Domenico Tintoretto and depict scenes associated with Saint Mark, the patron saint of the scuola.
Did you notice the double reflection in the mirror?