Barcelona, seen from Parc Guell ( top photo). To the left the  Forum area, in the middle Port Olympic. You can see the two towers. More to the right is Port Vell, the old town and Rambla area. 
 

Barcelona is a popular all year destination. However from the middle of August to the middle of September, it can be very hot. You meet many younger tourist here.

Barcelona is not very suitable for families with smaller children. However there is a 5 km long waterfront with beaches. It starts from Barcelonetta in Port Vell and stretches to Forum.

http://en.wikipedia.org/wiki/Barcelona for more details about Barcelona.
http://www.tmb.net   Transport information, local.
http://www.emt-amb.com  Transport information, local.
http://www.renfe.es Transport information, intercity and long distance. Train

http://www.barcelonaconnect.com  Web in English. French, Spanish and Dutch, with all the information about Barcelona you need. Active forum. Activities. Clubs, restaurants, bars. Travel tips. Transport inside and out of Barcelona.