The church at the top of Castle Hill is the oldest building of the town. According to the archaeological research in the middle of the 1950s, the church got its final form in four bigger phases.
The nave was built between 1241 and 1283 with a sanctuary and sacristy having square termination. It was almost totally demolished by the bailiff of Visegrád during the devastation of the town. It was then rebuilt in Gothic style in the 14th century, when the final ground-plan was formed. The church was almost totally ruined again during the Ottoman period and was only reconstructed in the 17th century. The next reconstruction and enlargement in Baroque style happened with the aid of the Zichy family in 1710. Historians think that Franciscans had already been serving in the town at that time because the church got a white plaster-work with red bands around the windows. The last significant reconstruction, when the church got its final form, took place between 1742 and 1751.
The parish church is listed as a historical monument since 1957. An overall renovation of the church was performed in the 1990s. In the historical centre of Szentendre, at the top of the Castle Hill the building, originating from the Middle Ages, draws attention even from a great distance. It has an east-to-west orientation and a projecting bell tower with pyramid hip roof . The floor space of the church is 200 m2. The tower, which has a height of 28.91 metres and a clock from the 18th century, has a cross at the top of the spire with pyramid hip roof. The clock got an electronic winder in 1970. The latticed window of the tower has a round arched closure, all other windows of the church have segmental arched closure. The single sectioned buttresses along the walls are Gothic. There is a sundial on the buttress, under the tower, at a height of 5.8 metres. It was carved from a single stone in the 1300s and it is a unique relic of the history of astronomy in Hungary.
The sanctuary ends with three sides of the octagon. Two entrances are on the southern side: one below the tower and one in the middle of the nave. The gates have Gothic stone frames.
Inside there is a single nave of 13.27 metres height, 35.4 metres length and 11.8 metres width. The ante-chapel below the tower is separated by a wrought-iron lattice. There are three giant Early Baroque groin vaults between its crosspieces, which are lying on crowned pilasters. The sanctuary is topped by a double sectioned, intersecting groin vault.
There are three side altars. The altar for the worship of the Pietà was erected along the northern wall. It was made by Teleky Károly in 1871, showing Virgin Mary and Jesus in the tomb. The statue of Saint Barbara and Saint Catherine can be seen on the altar, next to the painting. The previous altar was of Blessed Virgin Mary, provided with an indulgence from Pope Pius IV in 1776.
On the sides of the sanctuary the altars of the Biblical Magi and Saint Andrew can be seen. The altar of the Biblical Magi consists of two paintings and was made in 1748. The lower painting represents the Biblical Magi paying their respect to Jesus. The upper painting depicts Jesus giving the keys of the kingdom of heaven to Peter. The statue of Saint Margaret Mary Alacoque can be seen left to the pediment of the superstructure, with the statue of Saint Margaret on the right and the statue of the archangel Saint Michael at the top. The altar of Saint Andrew from 1755 can be seen on the other side of the sanctuary. It also has two paintings. The lower one shows Saint Andrew with two statues on the sides, the statues of Saint George and Saint Elizabeth of Hungary. This is a rare representation of Saint Elizabeth of Hungary without roses. The upper painting shows Mary with the Baby Jesus, with the statues of Saint Stephen I and Saint Emeric of Hungary on the sides and the figure of God and the Holy Spirit above.
The pulpit is placed next to the altar of the Biblical Magi. On its parapet there are the four Evangelists, on the sounding board there is Jesus with a cross, and on the inner part of the sounding board there is a dove symbolizing the Holy Spirit. The painting on the main altar in the sanctuary depicts John the Baptist and the baptism of Jesus with the figures of God and the Holy Spirit at the top. The highest point of the altar is a God’s eye symbol carved from wood. The painting of the altar was made by Carolus Schöfft from Pest to replace the two former paintings in 1818.
The Ecclesiastical chair in the sanctuary was made of wood, the Good Shepherd, the papal tiara and the Holy Crown of Hungary are carved on its back. The baptistery is from the 18th century. It is worth to also mention the bronze chandelier in the centre of the nave, made by Szemián Ágoston in 1909.
The frescos on the walls were made by the members of the Painter Association of Szentendre (Bánáti Sperák József, Onódi Béla, Jeges Ernő, Heintz Henrik and Pándy Lajos) between 1933 and 1938. These paintings are extraordinary because they show the biblical scenes with a background of Szentendre. On the left side of the main altar there is the news-bringing angel. On the right side there is the Angelic Salutation. The figures of God and the Holy Spirit can be seen above. On the northern side wall one can observe the paintings of the Biblical Magi paying homage to Christ, the 12-year-old Jesus in the church, Jesus and Mary Magdalene at the house of Simon (with the Parish Church and the Orthodox Cathedral in the background) and the whipping of Jesus in the presence of Pilate. Above the triumphal arch the meeting of Jesus and his 12 Apostles is depicted and to the western side wall, the figures of Peter and Paul and the Ascension of Jesus were painted. The painting on the ceiling shows Hungarian saints like Saint Stephen I, Saint Elizabeth of Hungary, Saint Ladislaus I or Saint Margaret of Hungary paying homage to Mary. The four corners of the ceiling fresco bear the symbols of Matthew, Mark, Luke and John.
The church has four bells. The big bell was consecrated to Saint Andrew. It weighs 594 kg, has a lower diameter of 106 cm and a sound of F#. This bell was cast by Walser Ferenc in Budapest in 1928. Apostle Andrew can be seen on the bell with a cross and the following inscription: “The bell of Saint Andrew, when you toll, may every toll of yours call the heretic to the hassock of the Lord”. The bell of Saint Joseph weighs 350 kg, has a diameter of 86 cm and a sound of B. This bell was made in 1948, in the workshop of Szlezák Rafael in Rákospalota to substitute the previous bell that weighted 366 kg and was taken away during the Second World War. A part of its inscription states: “Saint Joseph, protector of the Sacred Family, be our guide in our life and our patron in our death!”. The exterior of the bell bears a relief of Saint Joseph. The small bell weighs 196 kg, has a diameter of 30 cm and a sound of C#. It was consecrated to Saint John the Baptist. Its inscription is the following: “Our Lady of Hungary pray for us! Every toll of mine is a beat of the Hungarian nation’s heart, a supplicatory prayer for Greater Hungary and for the Resurrection of Hungary. From the followers’ donations, for the worship of the patron of the church, anno domini 1926. Walser Ferenc Bp.” The baptism of Jesus in the waters of the Jordan River can be seen on the exterior of the bell. The funeral bell weighs 27 kg and has a diameter of 38 cm. It was cast by Hegedűs József in 1843, hence being the oldest bell of the church. Its Latin inscription is the following in English: “Lord Jesus, receive my spirit!”.