Originally Posted by hhEb09'1

As near as I can tell, Matilda was married to a Holy Roman Emporer, but not crowned Empress, and died in Normandy near Rouen. The Cathedral in Rouen where she is buried is Notre Dame du Rouen, made familar by the many studies done by Monet. It also has the heart of Richard the Lion-Hearted. It is not the Notre Dame in Paris, of course. Apparently, it was the tallest building in the world, for four years, when its cast iron spire was erected. The Eiffel Tower, twice as tall, was built ten years later.

Find A Grave link
Empress Matilda wiki
Rouen Cathedral

That last link says the rest of Richard the Lion-Hearted lies at Fontrevaud Abbey (Fontrevault Abbey, in Maine-et-Loire, in the Loire Valley south of Normandy) but the link below explains that the body parts were removed during the French Revolution.

Fontevraud Abbey wiki
Western Franch Tourist Board