Helgoland is a group of two islands in the North Sea about 50 miles off the German city of Cuxhaven. The main island is a red sandstone monolith surrounded by steep cliffs with one tall, free-standing column of rock known by the name of ‘Long Anna.’ The lighthouse on Helgoland is the strongest on Germany’s North Sea coast. The islands were once joined, but erosion and rising sea levels have separated them. In its checkered history, Helgoland has more than once been fortified as a sort of ‘Gibraltar of the North’ by Germany. Following WWII, the British government destroyed the fortifications on Helgoland in what is believed to be the largest non-nuclear explosion in history, actually altering the geography of the island. The cliffs of the island and Long Anna are ideal breeding locations for seabirds, and a permanent bird observatory keeps track of the colonies of gannets and other seabirds nesting there.