Alderney's attractions are mostly outdoors and mostly free. The cliff walks that circle the island offer dramatic views of the Race — one of Europe's fastest tidal streams — and easy access to seabird colonies. The island's WWII history is present everywhere: German fortifications, bunkers, and the sites of the four Nazi forced-labour camps can be visited. The Alderney Railway, the only working railway in the Channel Islands, runs along the north coast. For those interested in birds, the colonies of gannets, puffins, and auks on the surrounding stacks are world-class.