The Oudegracht in Utrecht is a street with a second street underneath it. Dug by hand in the 1100s, this canal runs about two kilometres through the old centre, with quays at water level far below the pavements.

Those lower quays are lined with more than 700 vaulted wharf cellars. Merchants rolled barrels of wine, peat and cloth from boat to storeroom, no staircase required. When railways took the freight in the 1800s, many cellars flooded or filled with junk. Today they hold cafés, jazz clubs and candlelit dining rooms.

VoiceMap’s tours take you down to the water. You’ll see how the cellars worked, find the sloping ramp where goods came ashore, and meet the stone city castles that were built to show off wealth, not to withstand a siege.