In 1340 it was reported that the treasure of the church was kept in a dark vaulted room on the lower floor of what is called the double chapel. The double chapel is one of the oldest surviving parts of the church and dates back to the 11th century. It was built adjacent to the northern transept and can only be accessed via the cloisters. This seems to have been the permanent location of the treasury until 1873, when it moved to the former refectory and chapter school. After the restoration of the double chapel in 1982, the treasury was once again housed in its original location. The treasury now occupies both floors of the double chapel and a side room on each level. The basement floor with archaeological excavations has been made accessible. The entrance to the treasury, via the East wing of the cloisters, is on Keizer Karelplein, which is also the main entrance to the church.
The collection
The treasure of the Basilica of Saint Servatius traditionally consists of four parts: 1. the so-called Servatiana, objects traditionally associated with the life of Servatius, 2. relics and reliquaries, 3. liturgical implements and 4. ancient fabrics. The church's art collection and various archaeological finds are not part of the treasure but are also exhibited in the museum.
Servatiana
The key of Saint Servatius: decorative key, one of the attributes of the saint, silver.
Pectoral cross of Saint Servatius: silver and golden cross, with enamel and gemstones, a gift to the church from the duke of Bavaria.
The cup of Saint Servatius: millefiori glass, Roman.
The Crozier of Saint Servatius: wooden staff with ivory crook.
Portable altar of Saint Servatius: green serpentine stone with silver ornaments.
Reliquaries
The 'Noodkist': the reliquary shrine of Saint Servatius, an oak wooden chest, covered with gilded copper and decorated with enamel, vernis brun, cabochons and filigree. The 'Noodkist' was originally positioned on the main choir of the church and was accompanied by four panels, that in 1843 were sold and are now in the Royal Museums of Art and History in Brussels.
Another important piece is the tall patriarchal cross with relics of the True Cross, made by the Maastricht silversmith Master Ulrich Peters, around 1490.
Liturgical implements
This part of the treasure suffered most during the French period. Many chalices, patens, monstrances and other liturgical objects made of gold or silver were melted down in order to pay the war taxes that the French demanded from the canons. However, a few liturgical vessels from the Middle Ages survived and quite a few from the Baroque period are still in the collection.
Textiles
The medieval textiles collection of the Basilica of Saint Servatius is counted among the most important of its kind. From 1989 till 1991 the textiles were carefully restored and documented by specialists from the Swiss Abegg-Stiftung in Riggisberg. Among the best pieces in the collection are the so-called albe of Saint Servatius and the robe of Monulph. Furthermore, there is an extensive collection of early-Medieval woven silks from Constantinople, Egypt and Central Asia and various medieval woven materials from the Meuse-Rhine area, Spain, Italy and the Middle East.
Archaeological excavations took place in the double chapel in 1981-82. Underneath the ground level floor of the Sacrarium inferior canons' grave stones were found, some dating back to the 13th century. Also, parts of walls were excavated that at the time were interpreted as the remains of a Carolingian polygonal church. As it turned out, the walls belonged to polygonal transept arms of a 10th or 11th century church. These remains can be seen in the basement underneath the treasury. Part of the archaeological collection is on display in the lapidarium in the eastern crypt. An important find was the 1086 funeral cross of Humbert, who was provost of the chapter of Saint Lambert's Cathedral in Liège and Saint Servatius in Maastricht. It was he who had the double chapel built which is today the church treasury.