Lying 10km north of Irbid, between the hills of Tell Abila and Tell Umm Al Amad, are the remains of the Decapolis city of Abila. Largely unexcavated, the site isn’t set up for visitors, but you don’t need a guide to find the Roman-Byzantine theatre or the scattered remains of columns from the markets, temples and baths. Buses leave from Irbid's North Bus Station for Quwayliba (less than JD1, 25 minutes), near the site; ask the driver to drop you at the ruins.
The earthquake of AD 747 did a pretty thorough job of turning Abila into a rock-strewn field. However, if you’re looking for a real Indiana Jones experience and have a torch, you can explore the eerie tomb caves carved into the hillsides surrounding the site. The caves were once full of corpses, but tomb raiders stripped them clean over the millennia. However, the spectacular frescos adorning the walls and ceilings are marvellously intact and are made all the more dramatic by their remoteness.