Castle church in Szentendre, Catholic parish church on Castle Hill in Szentendre, Hungary

The Castle Church in Szentendre is a Roman Catholic parish church on Castle Hill, the town's oldest building. Its nave, chancel and sacristy were built between 1241 and 1283, and it was rebuilt in Gothic style in the 14th century, when the tower and current layout were added. The sanctuary closes with three sides of an octagon, and the south side has two entrances, medieval fresco traces, buttresses and stone-framed windows and doors.

The nave, chancel and sacristy were built between 1241 and 1283, but the church was destroyed in 1283 when the Visegrád ispán ravaged the settlement. It was rebuilt in Gothic style in the 14th century, when the tower and current ground plan were added. After partial ruin during the Turkish period, it was renovated in 1710 as a Baroque church with the support of the Zichy family, and its present form dates from 1742–1751.

The church's name recalls its original dedication to Saint Andrew, the town's patron; a 1717 bell bears the inscription "SS Andreas et Johannes ora pro nobis". Its kermis is held on 24 June, the feast of John the Baptist. Interior frescoes painted by Szentendre artists between 1933 and 1938 show biblical scenes set against views of the town.

The church stands alone in the middle of a small square on Castle Hill, with the tower and its 14th-century sundial facing the approach. Two entrances open on the south side, one beneath the tower and one at the middle of the nave. The parish keeps the building open around Mass; the annual kermesse falls on 24 June.

The tower's buttress carries a sundial carved from a single stone in the 1300s, noted for its importance in the history of astronomy. The tower's ornate spire collapsed in 1818 and was replaced by the present simple tent roof; its 18th-century clock was fitted with an electric mechanism in 1970.