St. Stephen’s Basilica is a Roman Catholic basilica in Budapest, Hungary. It is named in honour of Stephen, the first King of Hungary , whose right hand is housed in the reliquary. It was the sixth largest church building in Hungary before 1920. Since the renaming of the primatial see, it’s the co-cathedral of the Roman Catholic Archdiocese of Esztergom-Budapest. Today, it is the third largest church building in present-day Hungary.

More details: https://en.wikipedia.org/wiki/St._Stephen%27s_Basilica