This contribution concerns the relationship between the hydrogeological and archaeological characteristics of Solunt and Tindari (North Sicily), within the framework of the Watertraces project. The two cities face the Tyrrhenian Sea, on the northern coast of Sicily, are characterised by a relatively recent urban history compared to other Greek or Phoenician cities, being founded in the 4th century BC. The Hellenistic-Roman city of Solunt was moved from the promontory of Solanto to Mount Catalfano after the devastation of the first in 397 BC. The new position of the habitat offered advantageous defensive conditions and allowed it to control a vast territory, from the Gulf of Palermo to the Gulf of Termini and the hinterland. The steep slopes of Mount Catalfano did not prevent the inhabitants realising a regular urban network. Considering the hydrogeological characteristics of the mountain, the rise of hydrothermal waters along fracking planes led to the formation of small surges which were used by the inhabitants and whose waters were collected through tanks and basins. In this way, the city could benefit from a double supply of water: precipitation and natural rises. Tindari is also located on a cliff overlooking the sea. The site was founded at the beginning of the 4th century BC. The city soon became an important commercial centre due to its advantageous geographical location. As for Solunt, the orographic features provided an important natural defence of the site, reinforced by powerful ramparts embracing the contour lines. The discovery of travertine formations close to a cistern underlines, as in Solunt, the importance of the hydrogeological context, here characterised by karst exes whose waters served the city and more probably the public area. In Solunt and Tindari, the hydrothermal and karstic springs are now dry. This could be related to a seismic event described in the ancient sources. We know in fact that the city of Tindari was shaken by several earthquakes during its history. One of them is reported to us by Pliny and dates back to the 1st century BC. Another one would have caused several devastations in the city during the late period. Ongoing analyses at the archaeological, geomorphological, hydrogeological and palaeosimological levels, coupled with geochronology and isotopic water geochemistry, little by little, we discover the history of the water supply and management of these two key cities of the Hellenistic-Roman Sicilian world.