Thieves have stolen stainless steel panels that were used to prop up an historic site in Leicestershire.
The priory was founded in 1235
The theft of the steel supports from the 13th Century Grace Dieu Priory near Shepshed resulted in approximately £100,000 damage.
The steel panels were used to support the remains of the ruin.
Leicestershire Police said "a lot of damage has been done" by the thieves who took the specially-formed plates from the site earlier this week.
English Heritage, which supported the restoration of the priory, is still inspecting the damage.
The priory dates back to 1235 when Rohese de Verdon founded the building for Augustinian canonesses.
It remained a place of worship until Henry VIII dissolved the nunnery in 1538, stripping the building of its pews, church windows and steeple.