The uncanny similarity among the three designs — the painstakingly protracted approaches to the galleries — underscores the challenges the architects faced when trying to preserve the essence of these museums while making room for the cafes, bookstores, event spaces and education departments that have become regular features of the contemporary museum experience.

But there is something else behind the uniformity of these plans as well. What were once eccentric creations have become polite and well behaved. Gorgeously crafted, they are about reinforcing the existing cultural consensus — not rebelling against it.