Mentioned for the first time in documents in the 13th century, the castle was built to protect the salt mines, river trade, the bridge over the River Inn and also to guard the old salt route.
The name is derived from its location on the corner by the panning houses, where brine was evaporated. "Egg" is derived from “Eck”, the German word for corner. During the 15th century the castle was enlarged to become a residence for princes. In 1567 Archduke Ferdinand II moved the royal mint here. The famous Georgskapellechapel and the official state rooms are not open to the public, but can be hired for weddings and special occasions.