The phrase "well known" is a common way to express familiarity with an object, place, or idea. However, there are many other ways to describe something that is familiar or popular. For example, synonyms could include "famous," "renowned," "popular," "noted," "celebrated," "infamous," "established," "commonly recognized," "widely known," and "acknowledged." Each of these alternatives brings a slightly different connotation to the term, which may be more appropriate for different contexts or audiences. By using a variety of synonyms, writers and speakers can add depth and nuance to their language, making their communication more engaging and effective.