The Prado celebrates its bicentennial； "I Visited the Prado 200 Times."

The Prado Museum in Madrid. Emilio Parra Doiztua for The New York Times

The Prado: As Spain’s national art museum celebrates its bicentennial, our writer — who has visited more than 200 times — returned to every gallery, vestibule and passageway.

I Visited the Prado 200 Times. Here’s What I Missed.

On the year of the Madrid museum’s bicentennial, our writer visited every gallery, vestibule and passageway to see if he had missed anything on his previous visits. He had.