The Early Christian monastery at Alahan occupies a terrace high in the mountains of Isauria in southern Asia Minor. Constructed in the second half of the fifth century AD, its remains include three churches, a baptistery, a colonnaded walkway running the full lenght of the site, and several subsidiary buildings. The complex was almost certainly funded by the Emperor Zeno (474-491). It stands as the finest achievement of native Isaurian stone-masons and sculptors. Alahan is a key site in the history of Early Byzantine architecture. The site was excavated and studied by Michael Gough, but publication was delayed by his early death in 1974; this full report has been completed by his collaborators.