Cuxhaven, Germany

Cuxhaven is a North Sea town of about 48,000 residents at the mouth of the Elbe, where the 30-metre Kugelbake wooden beacon has marked the boundary between the river and the open sea since 1704. From the 1985 Alte Liebe harbour wall, visitors can watch container ships pass along the world's busiest river shipping lane, while the 1813 Sahlenburg beach borders the 1,200-square-kilometre Wadden Sea, a UNESCO site since 2009. The town also holds the 1937 Fort Kugelbake, the world's smallest open-sea fortification, and an 1892 Hapag-Lloyd pier that began emigration traffic. Each landmark leaves one question about what the next tide will uncover.