Cirencester is a market town in Gloucestershire, England, 93 miles (150 km) west northwest of London. Cirencester lies on the River Churn, a tributary of the River Thames, and is the largest town in Cotswold District. It is home of the Royal Agricultural College, the oldest agricultural college in the English-speaking world founded in 1840. The town's Corinium Museum is well-known for its extensive Roman collection. The Roman name for this place was Corinium, which is thought to have been associated with the ancient British Cornovii tribe, having the same root word as the River Churn.The first reference to the town was by Ptolemy in 150 AD.