The paper provides some data through unannounced publications, notes and correspondences from Western and Vietnamese priests about Ke Cho - Thang Long Imperial Citadel during the 17th - 18th centuries. Their contents refer to some features of the location and architecture of the Citadel
the inhabitants, their life, their activities and the customs of the King's and the Lords' palaces
the political, economic, social and religious situations in the contemporary Thang Long. The author gives quotations, notes and comments of the accuracy of the above mentioned data.