What is a tower or other building with a powerful light at top, erected at the entrance of a port, or at some important point on a coast, to serve as a guide to mariners at night; a pharos called?

lighthouse — A tower or other building with a powerful light at top, erected at the entrance of a port, or at some important point on a coast, to serve as a guide to mariners at night; a pharos. (Webster's 1913.)