A lighthouse is a structure designated as such on a current reference map of the country where the structure is situated.At this moment I don't know if this definition works for every country under the sun. Maybe there are lighthouses that don't belong to the country where they are situated. Maybe there are countries without official maps or countries that keep those maps secret or inaccessible. We'll see.
A historic lighthouse is a structure that once was a lighthouse.
Main Entry: lighthouse Pronunciation: 'lIt-"haus Function: noun Date: 1622 1 : a structure (as a tower) with a powerful light that gives a continuous or intermittent signal to navigators 2 : BEACON