An ice house is a building used to store ice blocks. During winter time, ancient people would collect ice blocks cut from lakes or rivers, and store them in ice houses for the next year. These ice blocks were used to keep food fresh or cool down the summer heat.
In the past, there were five ice houses in the Forbidden City, but at present only four of them are still there. They were all constructed in a north-south direction, with the insides half underground. Each ice house could hold as many as 5,000 ice blocks cut from lakes or rivers near the Forbidden City. In 2015, these ice houses were transformed into a restaurant, but the original structure of the ice houses remains unchanged.