We arrive in Barcelona on Sunday May 20th and I just learned that Monday the 21st is Whit Monday. Does anyone know what we should expect as far as closures are concerned? What would be good alternatives that day? We will also have Tuesday in Barcelona.
We experience Whit Monday in France...lots of things were closed, including our car rental agency.
I believe if you check the websites of the major Gaudi sights, you will find that they are open. Monday is a day when a fair number of museums in a lot of European cities close, so you may encounter that. But I am confident that in Barcelona, of all places, you will not run out of available things to do. Your guidebook should make it clear which of the key local sights are regularly closed on Monday, but I have occasionally seen notices on websites (not necessarily in Barcelona) that indicated that the museum, normally closed on Monday, was open on Monday holidays.
If you don't have a guidebook, you need one. Barcelona is an extremely popular destination, and a guidebook will help have the best possible experience as you try to focus on what interests you most while dodging the crowds.
Many of the top sights in Barcelona pretty much require pre-purchased tickets unless you are prepared to wait an hour or longer in a ticket line (possibly not even getting in). The ones that I'm aware of are:
Camp Nou soccer experience (sells out early, I think)
La Sagrada Familia
Parc Guell
Casa Mila/La Pedrera
Casa Batllo
Picasso Museum (tends to be unbelievably crowded; skip it if not a big fan)
Palau de la Musica Catalana (requires a tour, frequently offered in English)
Palau Guell (tends to be less crowded but often has a line)
The lovely Sant Pau modernista site still hasn't been fully discovered; you can normally walk right in. The city has many other museums that tend to be not excessively crowded (unlike the Picasso). And of course wandering around the historic district is good for several hours. There are walking tours of that area. I really liked the one offered by the local tourist office.