The sacristy of the old parish church dedicated to St Nicholas of Bari is located in Triq il-Knisja l-Qadima in Siġġiewi. The sacristy abuts the remains of the old parish church of Siġġiewi which were scheduled in 1998. Part of the sacristy is still accessible from the church while another part was converted into a dwelling. This property is the only surviving part of the old parish church not in ruins. The property is historically significant in view of forming part of the original church that was already documented in the 15th century.

The property appears to be a two-floor dwelling with a single door at ground floor and a small window at first-floor level. The property abuts an orchard fronted by a low wall with a palisade in the middle of which is a niche overlying a small doorway. A parish cross is also located next to the doorway leading to the orchard which was the site of the original parish church.

Mepa scheduled the sacristy for the old parish church as a Grade 1 national monument as per Government notice 1225 dated December 10, 2010.