Le Marché de Nuit -- "The Night Market" -- is said to exist in the Catacombs deep under Butte aux Cailles, with connections up into Our Lady of Liberation Hospital. Le Marché de Nuit is said to be one of the best places to find exactly what you're looking for, no matter how dangerous or forbidden might be. In addition, common rumor has it that every three months a silent auction is held to sell of especially unique or rare items.
It is also said to be the best place in town to get knifed and left for dead.
Le Marché de Nuit as an origin / destination is considered 'Obscure'.