A lighthouse is a tower designed to emit light, we all know that! Lighthouses span thousands of years. Light was first emitted from a fire. They were used as an aid in navigation for ships at sea or on inland waterways. They also mark dangerous coastlines, hazardous shoals and reefs, and safe entries to harbors, and can also assist in aerial navigation. I always think of the movie Puff the Magic Dragon when I think of lighthouses. That part of the movie must have traumatized me when I was a kid.
Once widely used, the number of operational lighthouses has declined due to the expense of maintenance and replacement by modern electronic navigational aids. One lighthouse that is really cool, and still functioning is actually a twin lighthouse in Navesink, New Jersey. You can tour the lighthouses, and on a clear day, you can see the Statue of Liberty from them.