Plas Mawr was built in the town of Conwy between 1576 and 1585 by Robert Wynn. Robert came from a prosperous local family and entered the service of first Sir Walter Stonor and then Sir Philip Hoby, both administrators and senior officials to King Henry VIII. Robert fought and was injured at the siege of Boulogne in 1544, took part in military campaigns in Scotland and traveled extensively across Europe. He invested in land across North Wales and married his first wife, Dorothy Griffith, a member of the local gentry, in 1570. Once married, Robert needed a suitable house and chose to settle in Conwy, a prosperous town that was known in the 16th century for its genteel society.