The ancient tradition of the art of memory builds palaces in the mind in which to place images that help us to remember. While this tradition may at first sight appear radically remote from the world we live in today, it nevertheless regularly resurfaces in different forms. I would like to describe the most famous ‘theatre of memory’ of the Renaissance, the Theatre of Giulio Camillo, and draw comparisons with some other ‘memory palaces’ of the 20th Century. Giulio Camillo appears to be quite an eccentric figure. He was a poet and master in the art of rhetoric, a magician and an alchemist, and a friend of many poets and great artists (amongst them Titian) who in the mid-Cinquecento devised a utopian project: a theatre of memory meant to contain all the existent knowledge and to offer models for the production of new texts and new images. What were the grounds for that project? And why is it still alive, for some aspects, in several 20th-century projects, such as The Encyclopaedic Palace of Marino Auriti, which opened the Venice Biennale in 2013?