In 1948 the organization became part of the National Theatre and was called Tyl Theatre ( after dramatist J.K. Tyl ) . In 1990 , after some restoration , it became known again as the Estates Theatre . In 1948 the theater was renamed the Tyl Theatre ( after dramatist J.K. Tyl ) and would be known as such until 1990 when , at the end of an eight year reconstruction project , it became known again as the Estates Theatre .