Located opposite Mercado Central, Lonja de la Seda or Silk Exchange is a beautiful sprawling rectangular building with towers. A designated UNESCO World Heritage building, it was originally the site of local silk trade during the middle ages. The façade has some lovely, but naughty, gargoyles and the interiors depict a rich Gothic style. It comprises three parts, including the main hall which is an enormous, luxuriously decorated space with stunning columns and where the merchants used to meet for their dealings. The side wing or pavilion used to be the seat of the first merchant tribunal in Spain, while the upper floors feature main function rooms with rich ceiling and medieval art. The central tower was the place where merchants were sometimes jailed for failing to pay off their debts or to meet their commitments.