Where to Find the Restroom

There's only one restroom inside the Panthéon. It's about halfway up the staircase that leads from the crypt back to the ground floor. The easiest time to stop is on your way up after exploring the crypt.

Keep in mind that this staircase is one-way. If you need the restroom while you're touring the ground floor, you'll have to head down to the crypt, go straight ahead, and climb back up by that staircase. It's a bit of a detour, but it's the only way.