Thessalonica was founded around 315 B.C. by Cassander, King of Macedonia, on or near the site of the ancient town of Therma. He named it after his wife Thessalonike, a daughter of Philip II and a half-sister of Alexander the Great. In 168 B.C. it became the capital of the Macedonia Secunda and in 146 B.C. it was made the capital of the whole Roman province of Macedonia. Due to its port and location at the intersection of two major Roman roads, Thessalonica grew to become the most important city in Macedonia. Thessalonica was important in the spread of Christianity; the First Epistle to the Thessalonians written by Paul the Apostle is the first written book of the New Testament.