Research of the Pontificio Istituto di Archeologia Cristiana on the Lateran Baptistery during the last two decades has resolved some of the many questions left open by the excavations inside the Baptistery in the 1920s and around it in the 1960s. This research has been coordinated by the author and Federico Guidobaldi and has involved the PIAC, the Swedish Institute of Classical Studies in Rome, the Vatican Museums and the Swedish National Heritage board. As a result it has been possible to determine the octagonal plan of the first (Constantinian) phase of the Baptistery, identify the foundations of the Oratory of Santa Croce, ascertain the height to which walls of the Constantinian phase are preserved, and deduce that the reconstructions attributed to the fifth-century Popes Sixtus III and Hilarus must be part of the same project.Laser scanned models and 3D documentation has been created as an instrument for research and for reconstructions. There remain, however, important, unresolved questions and these are also explored int his chapter.How was the building covered?Did it have an inner colonnade?What was the place of the first phase of this structure in the development of Late Antique architecture?

In the 1540s, Piefrancesco Giambullari and Giovan Battista Gelli published books in which they argued that the Florentine language was not a debased form of Latin, but derived from Aramaic and Etruscan. Their claims divided the Accademia Fiorentina for a number of years, and earned them the nickname “Aramei.”They relied especially on the writings of Annius of Viterbo, whose fraudulent works seemed to them to provide information about the region and its people that was absent from Roman sources. Their arguments about language history were unsatisfactory to many; efforts to refute them effectivelyinspired years of further research. Yet even those who opposed them were interested in finding ways to study peoples, languages, and customs. Ancient models of historical writing focused on politics and public actions, but in order to study groups of people, customs, or languages, newer approaches were needed.