Gregor Kalas investigates the architecture of Late Antiquity and the early Middle Ages with a particular focus on the post-classical adaptations of ancient buildings and monuments. In his publications, Kalas explores the reuse of ancient structures by highlighting that architectural reconstruction engages with historical memories and the reconstitution of lapsed time. His monograph, The Restoration of the Roman Forum in Late Antiquity: Transforming Urban Space (University of Texas Press, 2015), traces the political significance of reestablishing links to the venerable past in downtown Rome during Late Antiquity. His co-edited volume, Urban Developments in Late Antique and Medieval Rome (Amsterdam University Press, 2021), sheds light on the vitality of the post-classical city. Support for Kalas’s research has been awarded by the National Endowment for the Humanities and the Mrs. Giles Whiting Foundation. Kalas has also pursued investigations of late antique urban landscapes by digitally reconstructing the center of Rome in order to reveal the ritual function of buildings and the topographical linkages between significant city spaces. Currently, Kalas’s research concerns the early medieval reuse of public buildings in Rome to establish charity centers such as the church of Santa Maria Antiqua.