Giovanni Giustino Ciampini (born Rome, 1633; died there 1698) was an ecclesiastical archaeologist. He graduated from the University of Rome as a student of law but soon devoted himself to archaeological interests, which an important office (Magister brevium gratiæ) in the Apostolic Chancery permitted him to pursue. He devoted himself to the collection of books, coins, and statues, and to the creation of scientific circles for the development of antiquarian learning; thus he founded, in 1671, a society for ecclesiastical history and, in 1679, an academy of the sciences, the latter under the patronage of his friend, Queen Christina of Sweden.
He continued the school of archaeological research begun by Onofrio Panvinio and Antonio Bosio, and carried on on a smaller scale by Fabretti, Boldetti, and Bottari, and later Padre Alarchi and Giovanni Battista De Rossi. Apart from some minor archaeological studies (1693), he has left two illustrated works, one a history of the ancient churches East and West, built by Constantine the Great (De sacris aedificiis a Constantino magno constructis, Rome, 1693), and the other a history of the art of mosaic (Vetera monimenta in quibus praecipua . . . musiva opera . . . illustrantur, Rome, 2 vols., 1690–99). Both works contain good illustrations of many ancient Christian edifices and mosaics that have since perished or suffered change and deterioration. His works were edited (Rome, 1747) in three volumes by Giannini.