House of the Stewards
From Tolkien Gateway
The House of the Stewards was a building in the Hallows of Minas Tirith capped by a great dome.[1]
Within was a wide vaulted chamber with shrouded walls. This was filled with marble tables upon which were carved forms of sleeping men - the tombs of the Stewards.[2]
Situated near the House of the Kings on Rath Dínen, this house was the location where Denethor II immolated himself on 15 March, T.A. 3019[3] destroying the building.[1]