Arriving on June 8th for first trip to Barcelona. Only there four days and want to get as much in as possible. Just read that Monday, June 10th is Whit Monday. Does this holiday cause tourist sights to be closed? Which major sights should I expect to be closed and which open?
I think you'll find that the major sights in Barcelona will be open, but you don't have to guess. Google for the official website for each place you want to go and check.
I don't recall any "main" site being close that day -keep in mind the principal "tourists" in our own museums are ourselves, so when it's a bank holiday, many residents also do "tourist stuff" in our own city. Furthermore note that many sites that are normally closed on Mondays do open on festive Mondays, such as June 10th 2019. But again, to ensure the site you want to visit is open, do check the individual website.