Roman city of Jerash is about 50k from Amman. It was first settled about 100 BCE. It became a great city of 25000 people. In about 125 CE Hadrian came for a visit and they built the magnificent arch to celebrate his visit. It been Christian city. and then became a Muslim city. There are still Christains living in the surrounding area. This area has been a crossroad from everywhere. It is even on the silk road as items were taken to the coast and shipped to Italy and France.
This city rivals Ephesus. There were only about 20 people looking at it.