During Roman times, Umm Qais was known as Gadara. It was a city of the Decapolis, a loose confederation of cities in the Roman province of Syria. Other members included Philadelphia (Amman), Gerash, and Damascus. Gadara thrived under the Romans, but quickly declined after their empire fell. It was a small village when Islam arrived in the seventh century, and abandoned soon after. Archaeological excavations did not begin until 1982.
The ruins here are not quite as well preserved as those at Jerash. There are two amphitheaters. The Temple of Zeus and a Byzantine church are also fairly intact. The remains of an eighteenth century Ottoman village is located in the southeast corner of the site. Umm Qais' signature is the unique dark coloring of the stones, a mix of limestone, marble, and basalt. There's also a visitor's center and souvenir shop where you can get more information about the ruins.
Reaching Umm Qais can be a difficult task. It's located about 110km north of Amman and there is no easy way to get there. You can catch a bus from Irbid, which in turn can be reached from Amman. It's easiest to hire a taxi, or drive. Umm Qais is definitely worth the trouble, though. The views of the Golan Heights are amazing, and few tourists visit, so there's a good chance you'll have the place to yourself.
Location: 25km northwest of Irbid
Hours: Open daily 08:00-17:00