Exploring the universe of web pages of the European environment dedicated to the study and cataloging of Theatre Architecture is the objective of this article. The text is presented as a navigation in which different scales are made. In each one of them web sites are analyzed and, with different optics, they expose the architecture of the theatres. It shows sites that were born with different motivations but share 2 Ar@cne, núm. 224, febrero de 2018 the interest to safeguard the theatrical architectural heritage and make it known and shared. They are useful tools for architects, cultural promoters, professionals of the performing arts and fans of theatre and architecture, visiting them could know and understand in greater depth the European theatrical architectural heritage.