The former Customs House, also known as the "old market" (antiguo mercado), has two entrances: one on the square, the other facing the river, with a staircase leading directly to the banks, where goods were unloaded. Within its walls, great amounts of gold, silver and commodities of all sorts were stockpiled here, before the building was converted into a market in the early 20C, a function it maintained until 1996.