See the castells at Avinguda de la Catedral, Barcelona, at 7pm on Saturdays through 15 September, except in August.

BBC: Human pyramids in Catalonia

They stayed there for about 100 years until the Spanish-American War in 1898, when they were transferred back to Seville, to the Catedral de Sevilla.

BBC: The mystery of Christopher Columbus��s legacy

After the city was re-conquered in the 13th Century, the mosque was converted into the Catedral de Sevilla, and its connecting tower reached its final 104m height in the 16th Century.

BBC: Seville's threatened architectural heritage