The calculated distance (air line) between Rosignano Solvay-Castiglioncello and Mestre is approximately 170 miles respectively 274 kilometers.
By car or train, the actual journey to Mestre is certainly longer, as only the direct route (as the crow flies) between Rosignano Solvay-Castiglioncello and Mestre has been calculated here.
Air line (approximately)
274 kilometers
148 nautical miles