Line 9 (Italian: Linea nove) of Metropolitana di Napoli was a planned line, which should have been connected 6 stations. The plan has been abandoned due to the lack of funds.
This line was planned at around 2000. It was also called the Line of the museums and should have been connected Colli Aminei to the National Archaeological Museum via the Museo di Capodimonte, providing an alternative route to part of Line 1. One connection with Line 1 and one with Line 1, Line 2 and Line 10 were planned.
- Museo (Line 1, 2, 10)
- Colli Aminei (Line 1)