Valencia Silk Exchange Hall (Lonja Seda Valencia). World Heritage Site. Spanish Review: The complex was built between 1482 and 1533 AD and was originally used for silk trade, and hence became known as the Silk Exchange Hall, which has been the center of commercial trading ever since. As a late Gothic architectural masterpiece, the grand trading hall is also a symbol of power and wealth in the main commercial cities of the Mediterranean region from the 15th to 16th centuries AD.