Five years on, investigators are still trying to solve the mystery of what started the blaze at the French religious and cultural landmark.

Five years after a devastating fire, Notre Dame Cathedral in Paris will finally reopen to the public. Here's what to know about the devastating fire and reopening.

But the architect formerly in charge of Cologne Cathedral in neighboring Germany fears that things are moving too fast.More than just a beautiful house of worship, Notre Dame is a French national treasure.