Now, the city of Barcelona has gone out and said that.. even if they doesn't encourage people to actually do that, it's a human right to walk around without clothes, wherever they want.. On streets, in stores, in parks etc..
That has always been sort of a "grey zone", as in Sweden..
Technically speaking, it's not against the law to walk around without clothes, but you always have that law of "Disturbing the general law and order". Nudity kinda falls somewhere between that, and nudity is sort of "moved" to areas... sort of.. out of sight, in a sense.. Sort of.. It's not ok to walk down the street to the store without clothes, but it's ok if you want to get a full tan on your porch/balcony/garden along the same street..