Remarkably, this vaulted space under the duomo's pulpit was totally filled with debris in the late 1300s and was only excavated and restored in 1999. Originally functioning as a cathedral entrance and confessional, it was decorated with 180 sq metres of richly coloured 13th-century pintura a secco ('dry' or mural paintings) covering walls, columns, pilasters, capitals and corbels. Fortunately, these managed to survive their ignominious treatment. Entry is included in the OPA SI and Acropoli passes.