Primarily lectures, notes and research materials on early Christian architecture.
Also 765 35mm slides of early Christian architecture and antiquities, made from illustrations in a wide range of published works and from postcards and private photographs.
Also 741 postcards and photographs mounted in 9 albums. The first five albums (FOS 5/1-5) relate to a tour of the Middle East (particularly Syria, Palestine and Turkey) made by Foster in 1953. These volumes also contain some pictures of sites and buildings in Greece and Italy. The other four albums (FOS 5/6-9) relate almost entirely to Italy, although there are a few pictures of buildings in Paris in FOS 5/8. The contents of all the albums strongly reflect Foster's research interest in early church architecture, but they also include some postcards on subjects as varied as the souks of Aleppo, Turkish folk dancing, and classical sites in Greece.