This edition of the so-called 'Collectio Avellana' was published in two volumes, with a Latin commentary, by the German scholar Otto Guenther (1864–1924) in 1895–8. The collection consists of 244 documents dating from 367 to 553, including many imperial and papal letters, acts and other material, compiled at some point in the middle of the sixth century. Some of the documents are unique, making the work an important scholarly resource. Guenther used the oldest and best surviving manuscript, now in the Vatican Library: the first volume consists of documents 1-104, and the second of documents 105-244, with appendices and indices. The material ranges from letters about the enlargement of St Paul's basilica in Rome by Theodosius I to disputes between Rome and Constantinople, and the brief schism at the death of Pope Zosimus: schism, heresy and the restoration of papal control are recurring themes throughout the compilation.