Une rue sous les voûtes

Beneath the Hôtel-Dieu, oldest hospital in Paris and still operating worldwide, at the level of the Seine, were the vaults. Built in 1620 and connected to the hospital, they were used for deliveries and wash house. The hospital was reconstructed in 1867-78 and in the 1860s the vaults were filled in. The vaults were also found on the right bank of the Seine under Quai de Gesvres. (https://www.unjourdeplusaparis.com/en/paris-reportage/lieux-disparus-paris-les-cagnards)