About 30 firefighters were called to a fire at the former eye hospital in Hereford.
The fire at the derelict building in Eign Street broke out just after 1600 GMT on Monday.
The area had to be cordoned off causing traffic queues while diversions were put in place.
No one was injured and crews stayed at the scene until about 2000 GMT.
Fire investigation officers are at the scene to establish the cause of the fire.