Cadzow Castle, now in ruins, was constructed between 1500 and 1550 on the site of an earlier royal castle, one mile south-east of the centre of Hamilton, South Lanarkshire, Scotland. The town of Hamilton was formerly known as Cadzow or Cadyou (Middle Scots: Cadȝow, the "ȝ" being the letter yogh), until renamed in 1455 in honour of James Hamilton, 1st Lord Hamilton. The castle sits above a gorge overlooking the Avon Water in what is now Chatelherault Country Park, but was previously the hunting and pleasure grounds of the Duke of Hamilton's estate of Hamilton Palace.