Complex sentence: He is the patron saint of Mechelen, where St. Rumbold's Cathedral has at its high altar an elaborate golden shrine containing relics attributed to the saint, and it is rumoured that his remains are buried inside the cathedral.
Split into simpler sentences: He is the patron saint of Mechelen, where St. Rumbold's Cathedral possesses an elaborate golden shrine on its high altar, containing relics attributed to the saint. It is rumoured that his remains are buried inside the cathedral.