The calculated distance (air line) between Acilia-Castel Fusano-Ostia Antica and Vatican City is approximately 12 miles respectively 19 kilometers.
By car or train, the actual journey to Vatican City is certainly longer, as only the direct route (as the crow flies) between Acilia-Castel Fusano-Ostia Antica and Vatican City has been calculated here.
Air line (approximately)
19 kilometers
10 nautical miles