The church is in Mainz city, the capital of Rhineland-Palatinate Land (state) in west-central Germany. The town was settled by the Franks starting in 459. By the 8th century, it had become a significant city within the Holy Roman Empire. Due to its location in the centre of Europe, it is particularly important to Christianity. It served as the capital of the Electorate of Mainz and was the seat of the Archbishop-Elector of Mainz, who was the primate of Germany.
St. John’s church was built a short distance from the shore of the Rhine in the city centre. With the construction of the new cathedral at Archbishop Willigis' time in 1036, St. John's became a collegiate church. The distance between the church and the cathedral is only about 35 metres. Other good orientation points allowing a better location of the church in the context of the city are: the main railway station Hauptbahnhof (1,3 km, 18 minutes walk), Römisches Theater railway station (800 m, 11 minutes walk), Schillerplatz (450 m, 6 minutes walk), or the Citadel (950 m, 14 minutes walk).