Lake Constance (German: Bodensee) is a lake on the Rhine at the northern foot of the Alps, and consists of three bodies of water: the Obersee ("upper lake"), the Untersee ("lower lake"), and a connecting stretch of the Rhine, called the Seerhein.
The lake is situated in Germany, Switzerland and Austria near the Alps. Specifically, its shorelines lie in the German federal states of Bavaria and Baden-Württemberg, the Austrian federal state of Vorarlberg, and the Swiss cantons of Thurgau and St. Gallen. The Rhine flows into it from the south following the Austro-Swiss frontier.
Lake Constance was first mentioned by the Roman geographer Pomponius Mela about 43 AD. He noted that the Rhine flows through two lakes, and gave them the Latin names Lacus Venetus (Obersee) and Lacus Acronius (Untersee). Pliny the Elder used the name Lacus Brigantinus, after the Roman city of Brigantium (today Bregenz). The lake is also colloquially known as the Swabian Sea (das schwäbische Meer).
A lighthouse is a tower, building, or other type of structure designed to emit light from a system of lamps and lenses and used as an aid to navigation for maritime pilots at sea or on inland waterways.
Lighthouses mark dangerous coastlines, hazardous shoals, reefs, safe entries to harbors, and can also assist in aerial navigation. Once widely used, the number of operational lighthouses has declined due to the expense of maintenance and replacement by modern electronic navigational systems.