The Stone Sacristy standing in the middle of Porrassalmenkatu Street is one of the symbols of Mikkeli. According to the latest studies, it dates back to turn of the 16th century. The sacristy was the sacristy, which was later added to, of a wood church built in the 1320s. The church was dismantled in 1769, but the stone sacristy remained. The sacristy was restored in 1900, when it received its tall brick gables, its shingle roof and a small steeple similar to those of wood churches from the Middle Ages. The stone sacristy has been used as a museum since the early 1930s. It is currently operated and run by the Mikkeli Museum Office.
The stone sacristy has religious items from Mikkeli and its neighbouring parishes from the 17th–19th centuries on display. The collection was collected by the Suur-Savo Museum Association in the early 1930s. The painted pulpit of Mäntyharju Church shows how decorating the church and its furnishings relayed the stories of Bible for illiterate church-goers, as well. In addition, the rod of the parish clerk was used to wake up dozing parishioners, is also on display. The exhibition also has domestic and foreign chandeliers and communion chalices from the 17th and 18th centuries.