The 29th Annual Walton lecture which is organized in honor of Gennadius Librarian, Francis R. Walton was delivered this year by Professor Robert Ousterhout of the University of Pennsylvania on “Byzantine Constantinople: Visualizing a City in Transition.” The Walton lecture brought crowds to Cotsen Hall on March 2, and, to the Museum of Byzantine Civilization in Thessaloniki where it was repeated for the first time ever, on March 4th. The Thessaloniki lecture was made possible thanks to the initiative and support of the Archaeological Institute of Macedonian and Thracian Studies, the Museum of Byzantine Civilization, and the European Center for Byzantine and post-Byzantine Monuments.