I made the mistake of going here first after a visit to the Templo de Debod, but of course, after scanning my bag and putting it in a locker, I found that they don't sell the two for one ticket here, only at the Descalzas, so I walked there, did that, bought some food at El Corte Ingles and came back for the afternoon showing.
Unlike the Descalzas, there is no English tour, so you are left to your own devices, shepherded by two security guards, one of whom looked like Andy Kaufman if he'd grown up. I had mixed feelings about this. The old nun at the other place was a bit tedious 'This is a statue this is a relic this is another chapel. this is the virgin mary etc' but she did give some information whereas here you are just left to guess really.
There were lots of great paintings, I think the Velasquez royal paintings were actually at the Descalzas, I may be wrong, however, see both, you're bound to see them. The church was very impressive, with a great altar, much better than the modern cathedral near the Palacio Real. But the real jewel of this place is the reliquario.
Yes, in the basement is an ancient room, with gorgeous paintings and gilt all over the ceiling, and floor to ceiling glass cabinets covering every wall. These enormous cabinets are filled with tiny glass windowed boxes, filled with skulls, bones, bits of skulls, fabric roses, ribbons and so on, and these are all the Christian martyrs, saints, nuns, bishops and so on considered holy enough to have their bones saved in a llittle box. This seems quite strange to us today but if you go to any Spanish cemetery they have a little shelf with a photo of their loved ones, and the wealthier people have a whole alcove with photos of all the dead there.
There were Christian martyrs from 72ad, and a vial of saints blood that turned liquid once a year. Well worth a trip. read more