One of the most beautiful places I've ever seen. Very nice location, in Plaza Cardenal Belluga, you can only see its magnificence once you enter the Plaza. It's breathtaking.
In August it was open in the morning, until 1.00 pm and in the evening after 6.00pm. There is a guided tour up in the tower and it's worth doing it, the view from the balcony is amazing and you get to listen to the bells as well. The explanations are in Spanish.
The Cathedral Museum is beautiful, displaying few of Salzillo's works. At the entrance of the museum there is a computer with an interactive picture of the cathedral facade, and it shows the story every statue on the facade, as you touch it.
To visit the cathedral and to take pictures inside it's free, but the tour is 5 euros (I think) and the entrance to the museum is also 5 euros, with the permission to photograph, and with 3 euros discount for people who take the tour as well.
It took me a great effort to get away from it, it was like something was holding me there and not letting me go.
Too bad I can only give it 5 stars.More