Due to fantastic bit of good luck, DD and I (27 and 62) will be in Barcelona for 6 days mid July. We like heat, so no problem there. We have both "done" the CityBus tours, cable car over harbour, cathedral and Gaudi places about a decade ago. Hotel is walkable to the beach, so that's some sunbathing taken care of! However, money is really tight so could anyone suggest things to do / see for free please? We're happy to use public transport and walk about. Inexpensive evening eating place recommendations would be very welcome too.