This third report of the Danish Archaeological Expedition to Bodrum is devoted to study of the terrace on which the Maussolleion was built. Seventy five trenches were dug in gardens and orchards to examine the extent and nature of the perimeter revetment and its facing wall, the surfacing of the terrace platform, and the foundation of the building that stood at its entrance, at the centre of the east side. Also included is a transcript of G M A Biliotti's diary recording excavations on behalf of the British Museum at the site of the Mausoleum in 1865 (with transcripts of inscriptions) and an account of the early history of marginally drafted masonry.