Notre Dame is every bit as impressive as you would think it is. I got there right before 10 and made my way inside and despite the signs saying no flash, flashes were everywhere. Respect the signs people, they’re there for a reason. Anyway, I took a lap around the cathedral and even paid my way into the treasury. €5 is one of the cheapest entry fees I've found so I had no trouble paying that much. After exploring the inside I headed around to climb all the way up the towers.