St. Sebastian is the oldest Catholic parish church in the city of Mannheim and one of the three churches of the Mannheim city pastoral unit in the city center. In Electoral Palatine times it was used by the Elector as a court church and received a magnificent interior by artists such as Bibiena, Verschaffelt and Egell. The furnishings were impaired by remodeling in the 19th century and damaged during World War II. Together with the Old Town Hall, St. Sebastian's Church forms a Baroque double building erected at the beginning of the 18th century, which is the oldest preserved structure in the city.
History
First church in Mannheim
Mannheim was first mentioned in the Lorsch Codex in 766. Since when there was a church in Mannheim is not known, a parish priest was first attested in 1309. In the Worms synodale of 1496, a visitation protocol of the parishes of the Worms diocese, the Mannheim parish church was described and it was recorded for the first time that St. Sebastian was the patron of the church and village. In 1556, Elector Ottheinrich introduced the Reformation in the Electoral Palatinate.
Nothing is known about the further fate of the old St. Sebastian's Church. However, it was probably demolished at the beginning of the 17th century, when Friedrichsburg Castle was built in place of the old village as a bulwark to protect the Protestant Electoral Palatinate and the Mannheim villagers had to move north of it to what is now the lower town of the squares. With the exception of a few years during the Thirty Years' War, Mannheim subsequently remained Protestant. The few Catholics were forbidden to practice the freedom of religion in public, so services were secretly attended in Seckenheim's St. Aegidius Church.
New construction of the church
In 1685, a Catholic branch of the Wittelsbach dynasty took over the Electoral Palatinate inheritance under Philipp Wilhelm, who decreed that the Catholics could share the use of the Reformed and Lutheran churches, and in 1701 Mannheim once again received its own Catholic parish. After the destruction of the Nine Years' War, however, only a simultaneum used emergency church and, from 1704, also the church of the Capuchin Abbey were available. In the meantime, the foundation stone for a town hall on the central Marktplatz had been laid in 1700 in the town of square F 1, on the west wing of which the municipality planned a weighing house with representation rooms on the upper floor. The Catholics, with the support of the city director, proposed that the main Catholic church be built on this site instead. Elector Johann Wilhelm approved the proposal in 1706 and the foundation stone was laid that same year on November 25. Auxiliary Bishop Peter Cornelius Beyweg consecrated it in honor of the Holy Trinity and the Beata Maria Virgo Assumpta (Assumption of Mary). The plans met with resistance from the representatives of the majority Protestant town, partly because they were to pay for most of the costs and the building was to be symmetrically based on the representative style of the town hall. Instead, they proposed to build the church in square N 1 near the Paradeplatz. This, in turn, was rejected by the Catholics because the building site was too poor and the regular cattle market was held there, so that in 1707 the Elector ordered the church to be built on the Marktplatz.
According to the plans of the Vorarlberg master builder Johann Jakob Rischer (1662-1755), the church was built under the direction of the engineers William Cour and Johann W. Nottum. Contrary to Rischer's original plan, the Elector ordered all parts of the building to be raised 10 feet, round-arched windows for the church, and that no dome be placed over the church. Instead, the church was given a high hipped roof, as was the town hall before it. It was consecrated on December 12, 1709, and probably consecrated episcopally on May 1, 1710. By tradition, Sebastian was adopted as the patron saint for the town church. After that, construction on the church continued until 1723, especially on the facade decoration and interior decoration.