The Church of St. John the Baptist was founded between 1360 and 1370 by the foundation of king Casimir the Great. The first mention of the existence of the parish dates back to 1408. In the fifteenth and sixteenth centuries, chapels were added to the one-nave church. The first was the chapel of the Holy Cross, the second chapel, now called the Rosary, was founded in 1481 by the townsman of Radom Jan Warcab. In 1495 the chapel of St. Anna was added and in 1500 the chapel of Baryczkowska. Around the middle of the 15th century a tower was built, which also served as a city guard. In the years 1630-1633 from the foundation of Jan Kochanowski, the vexillifer regni, late renaissance chapel was erected. In 1752 the vault of the nave collapsed. In the early nineteenth century the church was severely damaged. Its restaurant was taken in 1817-1838. The walls of the nave were raised, which was covered with a wooden ceiling, a new roof was erected, the tower was elevated and the facade was plastered. As a result of these changes, the western façade was given neo-gothic decor. In the years 1881-1889 the tower of the church was raised by the fifth floor. In the years 1908-1909, the church was completely rebuilt according to the design of architect Józef Dziekanski in neo-gothic style. The changes included the extension of the nave by one bay to the west, the liquidation of outbuildings from the south and the erection of the aisle and the new sacristy.
The church is orientated, it was originally a one-nave building, it was only at the beginning of the 20th century that the row of the chapels was rebuilt into the south, side aisle. The medieval building was also one bay shorter, it was extended towards the west in 1908-1909. On the northern side, in 1481, two bays of the Chapel of Our Lady were situated, which forms a kind of lateral, third aisle. To the east is located a slightly narrower, two-bay, three side ended presbytery. In its north wall there is a sandstone portal from the beginning of the 16th century. It leads to a square sacristy with a porch. Present sacristy is a construction from the early twentieth century, but it was built on the site of the original, medieval. On its floor there is a former treasury to which lead a stone staircase from the vestibule. From the north-west side, a tower from the second half of the 15th century is added to the nave and the chapel. At the bottom it was erected as a four-sided, octagonal on top, originally it had four floors.
The chancel is covered with a net vault with profiled ribs made of brick, while the main nave is covered with a net vault, but with ribs made of sandstone. The vault of the nave is modeled on the vault of the presbytery. The Chapel of Our Lady, the south aisle, the western part of the nave and the sacristy have diamond vaults from the early twentieth century. Chapel of Our Lady originally had a flat, timber ceiling, it also housed a small music choir with stairs that led to the tower.
Żabicki J., Leksykon zabytków architektury Mazowsza i Podlasia, Warszawa 2010.
Website fara.radom.pl, Kościół pw. św. Jana Chrzciciela w Radomiu – Fara.