At the mouth of the Nidelva, there have been boathouses, piers and warehouses since ancient times. Here the townspeople traded in goods from far and near.

In King Sverre's time, the piers were also used as defenses. Screens and passages were built towards the river. From here you could throw stones at the enemy. Magnus Lagabøte's bylaw from 1276 states, among other things, that the swallow, a walkway on the outside of the piers, must not be wider than three cubits; further that there should be a "drop drip" distance between the piers. The piers that are still preserved are located on both sides of the Nidelva - in Kjøpmannsgata, on Bakklandet, in Fjordgata and Sandgata. The oldest preserved piers are from the middle of the 18th century.