The nineteenth-century excavations on Thera and Therasia took place at two periods: the first in 1866 and 1867 and the second in 1870. The investigations uncovered the Late Cycladic civilization of Thera, although at the time this could not be assigned to a chronological context, in the absence of any parallels: Minoan antiquities, the Cycladic civilization and the Mycenaean sites on the Greek mainland were all still undiscovered. The archaeological finds could not, therefore, be appreciated in their true historical dimensions. The excavations occasioned by the eruption of the volcano in 1867–70 were characterized by the approach and methods of the period, including evolutionism and the nascent Palaeolithic archaeology. These excavations were almost forgotten about for 100 years, partly because they were not related to ancient literary sources (as with Schliemann’s excavations conducted a little later), and partly because they could not be exploited for national purposes. This article provides a chronicle of the birth and evolution of these investigations