The Cathedral Basilica of the Assumption of Our Lady is considered to be the main church of the Győr Diocese. It is located in the most ancient part of the city, the place where the Rába and the Danube meet, on what is known as Káptalandomb (Chapter House Hill) across from the Püspökvár (Bishop’s Castle). Apart from the Püspökvár, this is the city's oldest and most significant monument. One of Hungary's most important relics is kept here, Saint Laslo Herma. The eastward facing three-aisle basilica's classicist main facade boasts large, half-circle shaped windows, above is the tympanum with vases at its corners, behind is the tower capped with a Louis Seize style steeple. The bronze gate of the main entrance was created in 1938 by Bandi Schima, a craftsman of Győr. The north and south faces of the basilica feature red marble gates made in 1774. The cathedral was granted the rank of minor basilica in 1997 by Pope John Paul II.

The cathedral, built during the reign of Saint Stephan is unique in Hungary as it is home to three holy sites, the Herma of Saint Laslo, the Relic of the Weeping Virgin Mother and the grave of beatified Vilmos Apor can all be found here. In the lower room of the museum, visitors can get to know the story of the basilica's construction as well as its most important artistic artifacts with the help of tableaus and televisions. The old safe now features a showcase containing the liturgic treasures of the past 500 years. The tombstones of the bishops of Győr and other famous persons can be seen on the walls. The upper-level features a throne installation showing visitors the facial reconstruction of St. Laslo. Artifacts of the Hungarian cult of St. Laslo ornament the walls.

The 'knight king's' herma, apart from the Holy Crown and the Holy Right Hand, is Hungary's most important sacral artifact and the only faithful depiction of an Árpád Dynasty king. The masterpiece of goldsmith work can be seen in the Basilica Museum. The throne installation on the top floor of the church features a scientific reconstruction of Saint Laslo's face. The walls are ornamented by artifacts of the Hungarian cult of Saint Laslo.