The Cardo Maximus is the main colonnaded street of ancient Gerasa. It extends from the north end of the Oval Plaza to the North Tetrapylon, and is intersected by two other colonnaded streets: the South Decumanus at the South Terakionion plaza and the North Decumanus at the North Tetrapylon. It was first built with Ionic columns in the late 1st century CE, but was widened and changed to Corinthian colonnades in the 2nd century CE. The Cardo was the architectural center of the ancient city and so had many of the city's most important buildings accessible from it.

Source:

Khouri, Rami G. Jerash: A Brief Guide to the Antiquities. Amman: Al Kutba, 1988.