THE project of excavation at Cluny sponsored by the Mediaeval Academy of America was completed at the Munich time, and all of the data were brought to America. Field operations occurred in 1928, 1929, 1931, 1932, 1934, 1935, 1936, and 1938, and were far more extensive than was at first anticipated. Detailed preliminary publication was started in SPECULUM, iii (1938),p. 401, and continued in volume iv, p. 3, p. 168; p. 291, p. 443; volume v, p. 77, p. 278; volume vi, p. 3; volume vii, p. 23, p. 336; but the piecemeal character of the excavation and the fragmentary character of the finds made inexpedient the further publication on such an elaborate scale. The true value of the work will appear only when the widely ramified collateral studies and the intricate work of graphic restoration of the buildings at Cluny have been brought to fruition. Then it will be seen what a vital place the great abbey had in the architecture of the tenth, eleventh, and twelfth centuries. Meanwhile two books have appeared on Cluny. That which was published by A. and J. Talobre (La Construction de l'Abbaye de Cluny, Macon: Renaudier, 1936) prints some of our material which was used lacking a proper understanding with us. The Mediaeval Academy's mission has an obvious interest in forestalling the publication of gratuitous or erroneous hypotheses, and has stood ready to help and advise workers concerned with the Cluny problem. If the Messieurs Talobre had been more frank, it would be unnecessary to correct several basic errors in their book. Their book contains interesting material, but it must be used with great caution. The plan here presented as Figure 1 represents the abbey as it stood about 900 years ago. This plan is solidly based on a thirteen-year study of the extant remains, the Farfa Consuetudinary text (ca. 1042) and other eleventh-century Customs, the 'Denombrement' of 1623, the Prevost engraving of ca. 1670, the abbey plan of ca. 1700, and various related material. Comparison with the Talobre plan and perspective will show discrepancies too numerous to mention. The first church of the monastery, Cluny i (927) is wrongly located on the Talobre plan, and Cluny ii (ca. 955-981) comes off very badly. The sanctuary of this building is described as vouite in 1623, and the nave, where the excavations revealed strong spur buttresses, is described as arcuata in 1063; but the Messieurs Talobre insist that Cluny ii was unvaulted. There was in fact a general movement to vault Burgundian churches after the destructive Hungarian foray of 953. The case of the St Philibert of Tournus is well known. Still unpublished is the discovery of Miss Elizabeth Sunderland, who has shown that the Cluniac church of ca 940 at Charlieu was vaulted over during the period in question, with the use of certain features which are found also at Cluny ii. The well-known Prevost engraving of ca. 1670 shows portions of the superstructure of Cluny ii, but the