Hertford (/ˈhɑːrtfərd/ HART-fərd) is the county town of Hertfordshire, England, and is also a civil parish in the East Hertfordshire district of the county. The parish had a population of 26,783 at the 2011 census.
The town grew around a ford on the River Lea, near its confluences with the rivers Mimram, Beane, and Rib. The Lea is navigable from the Thames up to Hertford. Fortified settlements were established on each side of the ford at Hertford in 913 AD. The county of Hertfordshire was established at a similar time, being named after and administered from Hertford. Hertford Castle was built shortly after the Norman Conquest and remained a royal residence until the early seventeenth century.