The calculated distance (air line) between Acilia-Castel Fusano-Ostia Antica and Aprilia is approximately 20 miles respectively 33 kilometers.
By car or train, the actual journey to Aprilia is certainly longer, as only the direct route (as the crow flies) between Acilia-Castel Fusano-Ostia Antica and Aprilia has been calculated here.
Air line (approximately)
33 kilometers
18 nautical miles