Cos was one of the stops on Paul’s return from his third missionary journey. Acts 21:1 (NIV) “After we had torn ourselves away from them, we put out to sea and sailed straight to Cos. The next day we went to Rhodes and from there to Patara.”

Cos is a large, fertile island located 2.5 miles (4 km) off the coast of Asia Minor (modern Turkey). The island is 23 miles (37 km) long from west to east, up to 5 miles (8 km) wide north to south, and has a circumference of 65 miles (105 km). The total area of the island is 111 square miles (287 sq km). The highest point is Mount Dikeos, with an elevation of 3,000 feet (900 m).

Cos figured in the time of the Maccabees when Rome sent with the Hasmonean officials returning home a letter of safe conduct addressed to the magistrates of Cos (Josephus Ant. 14.10.15 §233). Jewish presence on the island in the Roman period is confirmed by an edict given by Julius Caesar in favor of the Jews. Not long after, Herod the Great donated money to support the office of gymnasiarch at Cos (Josephus War 1.21.11 §424). Another inscription from Cos mentions Herod Antipas (Richardson 1999: 208). In 32 BC, the island was annexed to the Roman province of Asia.

The first person in the ancient world to classify diseases, Hippocrates founded the first medical school on Cos in the 5th century BC. According to legend, his father was a direct descendant of the god Asclepius.

A temple complex to the healing god Asclepius was built on Cos beginning in the 4th century BC. The Asclepium (= Asclepius Temple) was built in stages over several centuries, but all are dated after the time of the island’s famous doctor, Hippocrates. The Asclepium benefited from the island’s temperate climate and hot springs. These springs, rich in sulfur and iron, were first used by Hippocrates (ca. 460-370 BC) to cure visitors.