The Decapolis ("Ten Cities"; Greek: deka, ten; polis, city) was a group of ten cities on the eastern frontier of the Roman Empire in Judea and Syria. The ten cities were not an official league or political unit, but they were grouped together because of their language, culture, location, and political status. The Decapolis cities were centers of Greek and Roman culture in a region that was otherwise Semitic (Nabatean, Aramean, and Jewish). With the exception of Damascus, the "Region of the Decapolis" was located in modern-day Jordan, one of them located west of the Jordan River in Israel. Each city had a certain degree of autonomy and self-rule.

The names of the traditional Ten Cities of the Decapolis come from the Roman historian Pliny the Elder (N.H. 5.16.74). They are:

According to other sources, there may have been as many as eighteen or nineteen Greco-Roman cities counted as part of the Decapolis. For example, Abila is very often cited as belonging to the group.

Except for Damascus, the Decapolis cities were by and large founded during the Hellenistic period, between the death of Alexander the Great in 323 BC and the Roman conquest of Coele-Syria, including Judea in 63 BC. Some were established under the Ptolemaic dynasty which ruled Judea until 198 BC. Others were founded later, when the Seleucid dynasty ruled the region. Some of the cities included "Antiochia" or "Seleucia" in their official names (Antiochia Hippos, for example), which attest to Seleucid origins. The cities were Greek from their founding, modeling themselves on the Greek polis.