There are 41 active Broadway theaters listed by The Broadway League in New York City, as well as 9 existing structures that previously hosted Broadway theatre. Beginning with the first large long-term theater in the city, the Park Theatre built in 1798 on Park Row just off Broadway, the definition of what constitutes a Broadway theater has changed multiple times. The current legal definition is based on a 1949 Actors' Equity agreement with smaller theaters in New York to allow union members to perform, dividing theater spaces in the city into the system of Broadway and Off-Broadway seen today. Current union contracts clearly spell out if a production is "Broadway" or not, but the general rule is that any venue that mostly hosts legitimate theater productions, is generally within Manhattan's Theater District, and has a capacity over 500 seats is considered a Broadway theater. Previous to this legal demarcation a Broadway production simply referred to a professional theatrical production performed in a theater in Manhattan, and the theaters that housed them were called Broadway theaters. (Full list...)