The derelict former Bletchley Park Pavilion was severely damaged in a fire last night.
Emergency services were called to the scene on Sherwood Drive near MK College at around 6.53pm.
More than 30 firefighters tackled the blaze at the two-storey heritage building.
Firefighters used four main jets to extinguish the fire and three crews remained at the scene into the night.
The blaze was close to the Bletchley campus of Milton Keynes College, and a spokesman has confirmed it was not damaged by the fire.
The pavilion, according to MK Heritage, was once used for cricket matches and hosted the annual Bletchley Show up until the 1960s.