When architects draw plans, they start by drawing walls. But what is a wall? What is behind it? What is inside it? The ubiquitous architectural element is at once a support, a canvas, a barricade, a boundary, and a political actor that enables both justice and injustice. Log 66: Walls addresses these questions and expands on these uses. For Kiyoshi Sey Takeyama, the wall produces and protects individual freedom, whereas Anthony Titus sees the wall as an instrument of simultaneous constraint and dependence. Elle Gerdeman, Iman Fayyad, Oscar Zamora, and Elizabeth Bowie Christoforetti probe into different residential walls to critique the culture of contemporary construction, while Courtney Coffman investigates the curtain as a partition. Dela Anyah and Sofia Boldrini, Rafael Urano Frajndlich, and Alexandre Benoit analyze experiments in wall-lessness in Accra and in Oscar Niemeyer’s only set design. Alternatively, walls also thicken into national divisions. Ben Fehrman-Lee and Vasily Sitnikov with SUPERFLEX explore borders and their afterlives. The wall’s role in protection and exposure is taken up by Adolfo Del Valle Neira, David Turturo, Erez Golani Solomon and Michael Fisch, who all view the wall as mediating the social contract between the individual and political reality. In Italy, Robert Kahn analyzes the Villa Giulia in Rome and Manuel Orazi revisits the monumental wall of a sferisterio in Macerata. Engaging with the legacy of walls, Andreas Lechner reinterprets a Herzog & de Meuron proposal for postwall Berlin, and gru.a designs a house inspired by Rio’s retaining walls. Finally, in acts of making, ŠA Atelier stacks bricks at the National Gallery of Art in Vilnius; Irina Prentice piles broken concrete blocks found in La Rochelle, France; and Qiong Zhang topples bricks near the first Great Wall of China.