Portencross Castle is built on the Firth of Clyde and dates back to the 14th century. It faces the islands of Bute and (a little further away) Arran.
The castle was scheduled in 1955. It is now managed by the Friends of Portencross Castle who have been able to open up the castle with the support of HLF and Historic Scotland.
During the Second World War the castle was surveyed by Vere Gordon Childe.