The free museum in Lisbon on the first Sunday saved me $60 on my whole trip
I was in Lisbon last fall and almost skipped the Museu Nacional do Azulejo because the ticket was 8 euros. Turns out every first Sunday of the month, most of the big museums there are free, and I only figured it out from a guy at my hostel. I hit three of them that day and spent the money I saved on a real dinner instead of grocery store bread and cheese. The tile museum alone was worth the walk, and I got in without paying a cent. Does anyone know other cities in Europe that do a free museum day like this?
Madrid does this too, like the Prado and Reina Sofia are free certain hours, not just first Sundays. The trick is going in the last two hours before close, it gets packed but you still get in. Berlin also has a free museum day once a month, I think it's the first Sunday too. Timing matters way more than people realize.