64.1°N

Reynisfjara is black because it was once fire. Lava met the North Atlantic, shattered into glassy grains, and the sea has been grinding them finer ever since.

Behind the sand rises a wall of basalt columns: six-sided pillars that formed as a thick flow of lava cooled slowly and cracked, the way mud splits in the sun. Offshore stand the Reynisdrangar stacks, what is left of a headland the waves have not yet taken.

In Reykjavík the same geometry comes indoors. The glass skin of Harpa, the concert hall on the harbour, was made with the artist Olafur Eliasson, its cells drawn from the island's basalt.