Baths of Caracalla

Roman emperors often built huge public bath buildings for the people of Rome to enjoy. The largest one, and one that also happens to be very well preserved so we can still see it today, was the one built by the Emperor Caracalla, about 200 AD. When you first came in, you went into a big courtyard with changing rooms around it. This was for exercising - stretching, jogging, or aerobics.
There were two of these exercise courtyards, one on each end of the bath building. They had black and white mosaic pavements with patterns. Above them, there was a wooden balcony that went all the way around, so you could watch the people who were exercising. You can still see the holes in the brickwork where the balcony was attached.