From the North Tower of Notre Dame Cathedral in Paris, one can see many other beautiful churches in the skyline. Nearby, also on Ile de la Cite is another Gothic style church with exquisite 13 c. stained glass windows, Sainte Chapelle. It was consecrated in 1248 and was part of the royal family residence until the 14th century. This church was also restored in the 19 century.
On a distant hilltop to the north, stands Sacre Coeur Basilica, a magnificent 20th-century Roman Catholic Church decorated with mosaics inside. Sacre Coeur and its quaint neighborhood Montmartre are also must-do destinations for any visit to Paris. I recommend climbing to the tower of Sacre Coeur as well for a fantastic view.