The calculated distance (air line) between Sant Feliu de Llobregat and Ciutat Vella is approximately 6 miles respectively 10 kilometers.
By car or train, the actual journey to Ciutat Vella is certainly longer, as only the direct route (as the crow flies) between Sant Feliu de Llobregat and Ciutat Vella has been calculated here.
Air line (approximately)
10 kilometers
6 nautical miles