Ireland, County Donegal, Donegal town, Donegal Castle, Main Hall.

Scotland, Perthshire, Blair Castle, Piper in traditional Scottish outfit playing the bagpipes beside a cannon at the castle.

Scotland, Inverness-shire, Urquhart Castle with Loch Ness in the background.

Scotland, Ross and Cromarty, Eilean Donan Castle with its reflection in Loch Alsh.

Scotland, Ross and Cromarty, Eilean Donan Castle, evening view looking out towards Loch Alsh.

Scotland, Ross and Cromarty, Eilean Donan Castle.

Norway, Oslo, Soldiers of the Kings guard at the Royal Palace.

Germany, Bavaria, Rothenburg ob der Tauber, Burgtor or Castle Gate, Detail featuring the Hot Pitch Mask for pouring hot oil, tar and other boiling liquids on uninvited guests.

Italy, Campania, Naples, Castel Nuovo, also known as Maschio Angioino.

Italy, Campania, Naples, Castel Nuovo, also known as Maschio Angioino.

Ireland, County Donegal, Glenveagh National Park, Glenveagh Castle built between 1867 and 1873 for local landlord John George Adair.

Ireland, County Donegal, Glenveagh National Park, Glenveagh Castle built between 1867 and 1873 for local landlord John George Adair.