Aeschylus, father of Greek tragedy, was also the first to realize the potential of drama taking place ‘inside’ and ‘outside’ – a change from his earlier plays which is quite clear from the Oresteia onwards; and although the Elizabethan theatre was unconcerned with the literal representation of place, exits and entrances were no less crucial to its dramaturgy. Along with the proscenium arch came the stage doors actors fought hard to preserve until the nineteenth century, when first the box set and then the dominance of naturalism required doors to be literalized – as essential for slamming in Ibsen as for the complex avoidance strategies of a Feydeau farce. In the following article, Arnold Aronson discusses the role of the door, actual, assumed, and iconic, in world theatre – and takes a lateral look at its significance in the TV sitcom. The author is Professor of Theatre at Columbia University in New York, and author of American Avant-Garde Theatre: a History (Routledge, 2000), American Set Design (TCG, 1985), and The History and Theory of Environmental Scenography (UMI Research Press, 1981). Arnold Aronson served as President of the International Jury for the Prague Quadrennial in 1991 and 1999, and will be Commissioner General of the 2007 Quadrennial. A version of this essay was presented at Brown University at the conference held in 2003 in honour of Don B. Wilmeth.