Niddry Castle is a fourteenth century tower house near Winchburgh, West Lothian, Scotland. It is situated near the Union Canal, and is adjacent to a large oil shale "bing", or waste heap.
The tower was built around 1500 by Lord Seton. Mary, Queen of Scots, stayed here 2 May 1568, after her escape from captivity in Loch Leven Castle. In around 1680, the castle passed to the Hope family and became part of the Hopetoun estate. The Hope family, now Marquesses of Linlithgow, hold the subsidiary title Baron Niddry. In the 1990s, Niddry Castle was restored as a private residence. Formerly a Scheduled Monument, the tower was de-scheduled in 1996 to allow restoration.
The four-storey L-plan tower has a corbelled parapet, and a turret in the angle of the "L", which was added in the 17th century. The basement is vaulted, and the hall was above, on the first floor.