Musée de l'Orangerie des Tuileries, 1 Place de la Concorde, Entrée dans le jardin des Tuileries, 75001 Paris
The Louvre? 3 hours minimum. d’Orsay? At least 2 hours.
Musée de l’Orangerie? In and out under 10 minutes.
This museum features 8 giant Monet Waterlilies paintings that actually are curved to fit the walls of the building (he painted them specifically for the building) Check out my pics for some perspective on their size - they are quite a sight and need to be seen to be believed.
Rumor has it that there was more art on the lower level but really, I came to see the Waterlilies. And 9 minutes later, I was off.