The Basilica of Saint-Pierre-Aux-Nonnains is one of the oldest Christian churches in the world still standing. Erected sometime in the 4th century AD, it was originally part of a Roman-era spa when Divodurum, the former name of Metz, was a major military and trade center along the Germanic frontier. Specifically it was used as a pagan gymnasium when Christianity in Western Europe was still in its infancy. It was one of the few buildings in the city to remain standing after the Huns passed through in 451 AD.
Metz was an important cradle of Frankish civilization, with both Merovingians and Carolingians tracing their ancestry to the place. After the conversion of Clovis I to Catholicism, Metz became a Christian stronghold. During the 7th century, the old Roman gymnasium was converted to use as a Benedictine church. During the reign of Charlemagne, Metz was almost chosen as the capital city of the newly founded Holy Roman Empire, an honor which was instead bestowed on nearby Aachen. Neverthless Charlemagne was apparently fond of the old church, and two of his sons were buried in what would later be designated the Basilica of Saint-Pierre-Aux-Nonnains.
Amazingly, the original Roman structure remained essentially intact throughout the Middle Ages. Apparently by the 16th century the old edifice was showing its age, and the Church moved out. It then spent over 400 years in service as a warehouse: a perfectly intact thousand-year-old building, one of the best preserved Roman constructions in the world, was then used for storage. Thankfully, its historical importance was recognized in the 1970s and the basilica was restored. It is now used primarily as a concert hall, a fitting tribute to its medieval musical heritage.
The interior is much less Roman in appearance than the exterior, as the whole place was renovated in the 10th century, and again in the 20th century. Although still designated as a Basilica by the Roman Catholic Church, the building’s use nowadays is for musical functions and exhibitions. It is certainly an ideal place to see Gregorian Chant music performed.
References:House of the Blackheads (Melngalvju nams) is a building situated in the old town of Riga. The original building was erected during the first third of the 14th century for the Brotherhood of Blackheads, a guild for unmarried German merchants in Riga. Major works were done in the years 1580 and 1886, adding most of the ornaments.
The structure was bombed to a ruin by the Germans June 28, 1941 and the remains demolished by the Soviets in 1948. The current reconstruction was erected from 1995 to 1999. Today the House of Blackheads serves as a museum and sometimes concert hall.