The Bergkirche was built in the early 18th century by Prince Paul Esterházy. Eisenstadt was the seat of the Esterházy family, and the church lies just short walk to the west of the family's main palace.
The Bergkirche is architecturally quite unusual and is built in two parts. The main section, the church proper, is approximately a square. The interior is in Baroque style. The ceiling takes the form of a dome, which was painted in fresco in the late 18th century.
A side chapel is dominated by a large marble sarcophagus, the tomb of the composer Joseph Haydn, who spent much of his career in Eisenstadt working for the Esterházys. The remains of most of Haydn's body have rested here since 1932; the skull was added (with due pomp and ceremony) only in 1954; for the reason for the disparity see Haydn's head.
The church still possesses its original organ, built in the 18th century by the Viennese maker Gottfried Malleck; the instrument has been restored to its original state, as it was when it was played by Haydn and Beethoven at the premieres of famous works. The original console, however, is no longer used but resides now in the nearby Haydn Museum.
References:The first written record of church in Danmark locality date back to the year 1291. Close to the church are several stones with a Christian text and cross inscribed. The oldest parts of the present red-brick church are from the 1300s. In the late 1400s the church was enlarged to the appearance it has today. The church has been modified both internally and externally several times, among other things after the fires in 1699 and 1889. There are lot of well-preserved mural paintings in the walls.