I visited Sevilla during Semana Santa, which is the holy week before Easter. Personally, I think that Sevilla felt the most Spanish, culturally-speaking, compared to Barcelona and Madrid. There was so much involvement with the whole Semana Santa thing. There was parading through the streets all day long, with people carrying big crosses and all decked out in the white cloaks and hoods. I visited the cathedral while I was there and climbed to the top. The climb is tiresome, but definitely worth it because the view from the top is incredible. There is also a Moorish palace called the Alcazar there which is really beautiful and definitely worth seeing, especially if you don't make it to Granada to see the Alhambra.