Basilica B is located at the archaeological site of Philippi and dates from the middle of the 6th century AD. This monument remains an enigma for the History of Architecture of Justinian period in Greece as it was never completed as a building. The present publication focuses on the presentation of the restoration study of the Basilica with regard to the fact that intervention measures should be limited so as to preserve the vestigial state of the monument. Also, aspects for the restitution of the initial structural system of the monument on a theoretical base are given so as to answer to questions left open from previous works of archaeologist Paul Lemerle and others.