The museum is housed in the Cathedral Chapter House, which was built in 1457, and served as a sacristy and meeting place for 100 years. After the Reformation, when the Dukes of Atholl became responsible for the upkeep of the church they used the Chapter House as their Mausoleum and it still contains some magnificent monuments and memorials. The Atholl coat of arms is mounted above the entrance door and former members of the family lie buried in an under floor vault.