Diocletian's Palace is an ancient palace built for the Roman Emperor Diocletian at the turn of the fourth century AD, that today forms about half the old town of Split, Croatia. While it is referred to as a "palace" because of its intended use as the retirement residence of Diocletian, the term can be misleading as the structure is massive and more resembles a large fortress: about half of it was for Diocletian's personal use, and the rest housed the military garrison.

After the Romans abandoned the site, the Palace remained empty for several centuries. In the 7th century, nearby residents fled to the walled palace in an effort to escape invading Croats. Since then the palace has been occupied, with residents making their homes and businesses within the palace basement and directly in its walls. Today many restaurants and shops, and some homes, can still be found within the walls.