From the MCSO website
When it was built in 1962, the First Avenue Jail was the first “modern” jail in the Valley, intended to house an average of 500 inmates in a “traditional” jail environment. This jail was closed in 1999 and does not currently house inmates.
In 2000, Sheriff Arpaio converted some areas to house abused animals. Any animal removed from an owner for criminal neglect or abuse by the Animal Crimes Investigations Unit can be housed at the First Avenue Jail. We now call this the M.A.S.H. Unit.Location: (Map It)
102 W. Madison Street
Phoenix, AZ 85003