Tunnel entrance at Mercatorstraat.
This is the only place with a separate tunnel entrance and exit, due to the narrow street.
This tunnel is used by line 9, the tunnel section is about 3500 m long with exit at the left bank of the river Schelde at Blancefloerlaan (photo:https://transphoto.org/photo/1936051/ ) .
Line 9 services the following metro stations: Plantin – Diamant – Opera (cross station) – Meir – Groenplaats – Van Eeden.