![Kirk Taylor McCoy in surgery](https://cdn.statically.io/img/static.wikia.nocookie.net/memoryalpha/images/a/ab/Kirk_Taylor_McCoy_in_surgery.jpg/revision/latest/scale-to-width-down/180?cb=20121022151607&path-prefix=en)
An operating room at Mercy Hospital
Mercy Hospital was a medical facility on Earth, located in the Mission District of San Francisco, California. This was a seven-story building with levels connected by elevators and stairs.
On the first floor, there was a nurses station, gender-segregated bathrooms, and a fire hose. On the second floor, there was an operating room. It also had a security corridor.
In 1986, Pavel Chekov was taken to this hospital when he suffered a torn middle meningeal artery, following his attempted escape from US Navy aircraft carrier USS Enterprise. (Star Trek IV: The Voyage Home)
According to the Star Trek Encyclopedia, 4th ed., vol. 2, p. 36, the scenes set inside Mercy Hospital were filmed in Centinela Hospital in Inglewood, California.