Interior of the Cat's Hostel in Madrid. It was converted from an 18th century palace. It sleeps up to 200 which is HUGE for a hostel, but since they cram 10-14 beds in some of the rooms, it's doable. It's right in the middle of the city and actually has a bar in the "basement"
If you're ever in Madrid, I highly recommend it (oh and they speak English there, too. www.catshostel.com