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Cambrai must have looked impressive to the 16th century traveller, with its five kilometre enclosure reinforced with bastions, its fifty towers and seven city gates.
The town extension unfortunately had reason for these fortifications in the 19th century; there are many remains however.
The most extraordinary is the network of underground countermines , constructed undre Charles Quint citadel of wich we can still see the gate, arsenal and barrack buildings.
The most curious is the "Porte d’Eau" (Water Gate) spanning the Escaut River, wich defends river access to the town using the three portcullisses whose mechanism still exists today.
The most moving can be found in the Château de Selles, where many prisoners’ graffiti is witness to its role as a prision.
The most precious are Notre-Dame Gate, in baroque style, Saint-Géry Church with Rubens’ "Mise au Tombeau" (The Entombment) and the cathedral housing Fénelon’s grave.
 mine gallery to prevent all underground enemy attack using explsive mines