Team Building in Essex. Essex is a county in southeast England, between London and the North Sea. The town of Colchester has Roman ruins and the Norman-era Colchester Castle, with a museum. Colchester Zoo is home to orang-utans and white rhinos. Southwest, 18th-century Hylands House in Chelmsford is set amid vast parklands. To the north is the medieval market town of Saffron Walden, home to Jacobean estate Audley End House and Gardens.