The West Lawn Building opened in 1913 and housed the Chronic Male Unit. Closed down in 1983, this building has been used sparingly for film work due to its rundown and unsafe state.
Sam wakes up from a nightmare outside the hospital and then the brothers go inside in episode 1x05 "Bloody Mary".
Dr. Vogel drives Ray and Nora up to the checkpoint to the West but their passage is interrupted by both of the Damian Darhks in episode 3x13 "No Country for Old Dads".
Mulder and Scully question Dr. Glass about their patients, and later Mulder explains his alien abduction theory to Scully in pilot episode.
From episode 2x11 "Excelsis Dei".
Source: Filmap
Gus and Shawn head to the metal hospital to find is condemned and locked.