The calculated distance (air line) between Áyios Konstandínos and Petroúpolis is approximately 130 miles respectively 210 kilometers.
By car or train, the actual journey to Petroúpolis is certainly longer, as only the direct route (as the crow flies) between Áyios Konstandínos and Petroúpolis has been calculated here.
Air line (approximately)
210 kilometers
113 nautical miles