East Citadel was once owned by an Emperor about whom little is known. High Roller used to serve him as a court jester, until he insulted the Emperor and was banished from East Citadel. It's currently unknown what happened to the former Emperor after High Roller usurped him.
It looks like a Chinese building, kind of like a palace, but there are roads, which can cause High Roller to have headaches because of the traffic. It can move to the side to reveal a sort of competition arena where High Roller challenges Big Green to different events.