In its final form, Roman Exeter (Isca Dumnoniorum) was a fine walled city nearly 100 acres in extent and entered by four gates. Streets were fronted by shops and houses built of stone or half-timbered. In the centre were public buildings, the Forum and the Baths. There would be pagan temples and probably a Christian church. The city was the product of 400 years of development and growth. This booklet tries to explain how it came about.