Its focus, the Church of the Immaculate Conception of the Virgin Mary and of St Phillip Neri, is the only building in Poland representing a purely imported Venetian version of full Italian Baroque. The church which stands on Święta Góra (Holy Hill) was designed by Baldassare Longhena, and is a replica of his Church of Santa Maria della Salute in Venice. Gostyń’s church was founded in 1675 by Zofia Konarzewska née Opalińska, who brought the famous architect’s plans from Italy.

The church represents the largest and best executed example of a 17th-century centralised church, in which an octagonal nave entirely dominates the chancel, flanked by radiating side chapels. The complex is homogeneous - neither the time it took to build it (over 100 years), nor the input of various architects upset its stylistic clarity. Its construction was supervised by the Swiss architects Giorgio, Andrea I and Andrea II Catenazzi, who saw the church raised to the level of its dome from 1679 to 1728. After a 30-year hiatus in construction, building work was completed by Pompeo Ferrari, who, built the dome according to its original design (17 m in diameter), a slightly altered gloriette and two frontal towers. The entrance is preceded by a terrace and radiating steps. Late Baroque stone figures dating from 1723-1726 and representing the Virgin Mary, St Phillip Neri and St Ignatius Loyola adorn the niches of the façade. The basilica’s underground vaults are also octagonal in plan and house extensive crypts covered by a low, semi-elliptical dome, concealing the remains of the founders and members of the Congregation.

Among the highlights of the church’s richly furnished interior are its late Baroque altars. The main altar was built in 1723-1726 by Ignazio Provisore and Johann Siegwitz. At its centre is a painting of the Virgin and Child (1540) featuring a landscape of Gostyń and Święta Góra in the background. Below this is a lavishly decorated Rococo tabernacle made by Tobias Plakwitz of Wrocław and Johann Hagemair of Augsburg (1759-1764). The illusionist paintings adorning the dome are of great artistic value. Depicting the life of St Phillip, they were produced by the Silesian painter George Wilhelm Neuhertz in 1746. The iconographic significance of the dome as a symbol of Heaven is heightened by the mouldings and frescoes, in particular the angels at the base of the dome with cartouches containing the eight beatitudes, indicating that St Phillip’s life was based on the evangelical beatitudes. The stucco pulpit, the organ front, choir stalls, confessionals and pews are also noteworthy. The Rococo fittings of the sacristy (1769-1774) are of particular value: its marquetry-decorated cabinets conceal magnificent liturgical vestments, such as chasubles and copes, as well as chalices and monstrances of the highest artistic merit.

Since the construction of the monastery in 1668, this site has been under the care of the Oratorians (with an interval during the period of secularisation in 1876-1919). The monastic complex consists of monastery buildings, gardens, a former hospital and a chapel by a miraculous spring. An inn, known as the Nadolnik, located at the foot of the hill was also once linked to the monastery. The monastery was raised as a quadrangular building enclosing a square courtyard featuring a well dating from 1774. A square turret surmounted by a sheet-metal cupola adorns the main façade. A small room next to the refectory houses the Święta Góra archives, including the oldest document pertaining to the sanctuary. Below the chapel is a library where valuable historic volumes and music manuscripts are kept.

Set amongst fields and orchards, the complex retains its original relationship with its surroundings, and the roads leading to the shrine of Our Lady of Święta Góra are the same as those of centuries ago.