Les Invalides & Napoleon's Tomb is a real time commitment — fit it in only if it's a priority.
Allow 1.5–2.5 hrs.
The gilded dome is a landmark in its own right, and beneath it Napoleon lies in a grand red-quartzite sarcophagus. The Musée de l'Armée is comprehensive — a lot for military-history buffs, a bit much for everyone else. The dome and tomb alone are worth the stop.