Two hundred metres north of the hippodrome is the imposing South Gate, which was likely constructed in AD 130 and originally served as one of four entrances along the city walls. Along the way you can see how the Roman city, then as now, spilt over both sides of Wadi Jerash, with most of the residential area lying east of the wadi. The visitor centre is on the right before the gate; hire a guide here.
One square kilometre of the city is encased by the 3m-thick, 3.5km-long boundary walls. Don’t forget to look up as you pass under the South Gate: like Hadrian’s Arch, the columns bear elaborately carved acanthus-leaf decorations and would once have supported three wooden doors. Framed by the archway is the first hint of the splendour ahead – the columns of the forum start appearing in ever greater profusion as you walk towards them.