Souris Valley Mental Health Hospital also called the Souris Valley Extended Care Centre was a public hospital in Weyburn, Saskatchewan. Originally called the Saskatchewan Hospital when opened in 1921, it was the largest building in The British Commonwealth and the most expensive building erected in Saskatchewan at that time. In its' beginning the hospital housed 607 patients.Weyburn's hospital was considered on the cutting edge of experimental treatments for people with mental health issues. The facility had a reputation of leading the way in therapeutic programming. At its peak, the facility was home to approximately 2,500 patients.