There are a few things that I'll always visit every time I go to Paris, and Sacre Coeur (Sacred Heart) is one. Of all the churches I've ever visted, this one is still my favorite, even though it's crawling with tourists, every single one of them taking the same pictures. There's always some guy playing pop songs on the guitar, and those weird dudes trying to tie strings around your wrists and scam you out of all your euro coins. But still, I find it beautiful despite all these annoyances.
If you've ever been to Europe — or just seen pictures of it — you'll know that every country has tons of amazing old churches and cathedrals. Unfortunately, they lose their impact because there are so many of them. After awhile, all the churches look the same. I like Sacre Coeur so much because it's so much different than the rest. The basilica is always bright white, even after 100 years of weathering and polution, because it's built from travertine stone, which exudes calcite (that's what Wikipedia said). Also, it's built on the highest point in Paris, so it has a great view of the city.
Sacre Coeur never loses its magnificence to me, and it doesn't hurt that it's in Montmartre, where a lot of Amelie was filmed. I would have loved if our hotel had been in this area. Although parts of it can be a little sketchy, I love the tiny windy streets with bistros and cafes. Also, a lot of souvenir shops, but you can try to ignore those. This is where Jake tried his first crepe and liked it! A small victory.