St. John's Archcathedral in Warsaw (Polish: Archikatedra św. Jana w Warszawie) is a Catholic church in Warsaw's Old Town. St. John's stands immediately adjacent to Warsaw's Jesuit church, and is one of the oldest churches in the city and the mother church of the archdiocese of Warsaw. It is one of three cathedrals in Warsaw, but the only one which is also an archcathedral. St. John's Archcathedral is one of Poland's national pantheons.