like here in the la barceloneta district, adjacent to the beach.nel martinez and his friends are on patrol. they've set up a district association to address a problem in the neighborhood. many apartments here are being rented out to tourists, most of them illegally. local residents are hanging up banners in protest. the activists say that soon there won't be any local people in the district. they're being pushed out, as more and more buildings are being converted to tourist accommodations. >> we've discovered that 1500 out of 8000 apartments are being used for tourists. local residents are being displaced in brutal fashion. as tourist numbers continue to rise, the neighborhood is being transformed into a party zone. non-stop action, 24 hours a day. >> a few frenchmen said it's the copacabana in europe. everything goes, an endless fiesta. when darkness falls in barcelona, the decibel level goes up in the city's hotspots. reporter: the noise continues until the middle of the night. for the people who live here, it's almost unbearable. in la barcelone