Scotland, Outer Hebrides, Isle of Barra, Castle Bay, Kisimul castle seen from the shore with moored boats in the foreground.

Scotland, Outer Hebrides, Isle of Barra, Castle Bay, Kisimul castle seen from the shore with moored boats in the foreground.

Scotland, Outer Hebrides, Isle of Lewis, Gateway showing pathway erosion.

Scotland, Outer Hebrides, Isle of Lewis, Gateway showing pathway erosion.

Scotland, Outer Hebrides, Lewis,Callanish standing stones.

Scotland, Outer Hebrides, Lewis,Butt of Lewis Lighthouse.

Scotland, Outer Hebrides, Lewis,Butt of Lewis Lighthouse.

Uzbekistan, Bukhara, Outer walls of the Ark Fortress, Registan Square.

Uzbekistan, Bukhara, Outer walls of the Ark Fortress, Registan Square.

Uzbekistan, Bukhara, Entrance, outer walls and viewing gallery of the Ark Fortress, Registan Square.

Uzbekistan, Bukhara, Entrance, outer walls and viewing gallery of the Ark Fortress, Registan Square.

Uzbekistam, Khiva, Akshi Bobo, a tower of Kunya Ark, on left, and outer wall of Ichan Kala.