One of the more popular graves was some famous romantic couple, like the inspiration for Romeo/Juliet or something.
I’ve read that they threatened to remove Morrison due to the crowds and disturbance.
He’s still there, but with a fence to keep the crowds back.
I think the next most visited grave is Chopin.
Google Heloise and Abelard
You're probably thinking of Abelard and Heloise. http://www.abelardandheloise.com/Story.html
It is the story of a 12th century Paris teacher and his student who fell in love.
The girl became pregnant and the couple was ostracized by the community.
They were forced to become priest and nun and she to give up her child, never to see it again.
Six hundred years later, it was Josephine Bonaparte, so moved by their story, the she ordered that the remains of Abelard and Heloise be entombed together at Pére Lachaise cemetery in Paris. To this day, lovers from all over the world visit the tomb where the remains of Heloise and Abelard rest eternally together.
Here is their tomb:
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