Castles and Cairns
A dramatic ruined castle on a high lochside viewpoint is often a feature of the Cowal landscape. Despite being built as strongholds many Castles, such as Castles Toward, Knockamillie and Asgog fell victim to the massacre of the Lamont clan by the Campbells in 1642, a dark period in the history of Cowal. Others, such as Dunoon Castle simply fell victim to neglect, with now very little left to see. Dunoon castle became the site of the historic Castle House in 1824 which is now the Dunoon Museum.

Castle Lachlan, dating from around 1314 was destroyed by fire in the 18 century. The decaying ruins stand on a promontory overlooking Loch Fyne near the village of Strathlachlan. Its double tenement internal structure is only one of two in Scotland. Carrick Castle on the shores of Loch Long, dates from the 12th Century and is thought to have had an association with Robert the Bruce. It was owned by the Campbells and destroyed by fire in 1685. It is currently under restoration.
Early settlements
Signs of much earlier settlements dating from over 3,000 years ago are evident in the Inveryne and Balliemore standing stones and the Ach-na-ha-cairn at Glendaruel. An excavation by the Cowal Archeological and Historic Society at the Ardnadam site near Loch Loskin revealed a site with a long history of settlement from 3.700 AD.