Musée du Louvre
The Louvre may be the most actively avoided museum in the world. Daunted by the richness and sheer size of the place (the side facing the Seine is some 700 m long) both visitors and locals often find the prospect of an afternoon at a smaller museum far more inviting. Eventually, most people do their duty and come, but many leave overwhelmed, unfulfilled, exhausted and frustrated at having got lost on their way to Da Vinci's Mona Lisa. (Lonely Planet)
Stendhal's syndrome is a psychosomatic illness that causes rapid heartbeat, dizziness, confusion and even hallucinations when an individual is exposed to art, usually when the art is particularly 'beautiful' or a large amount of art is in a single place (wikipedia).