The Llotja de la Seda (English: Silk Exchange; Spanish: Lonja de la Seda) is a late Valencian Gothic style civil building in Valencia, Spain, built between 1482 and 1548, and one of the principal tourist attractions in the city. The UNESCO considered it as a World Heritage Site in 1996 since "the site is of outstanding universal value as it is a wholly exceptional example of a secular building in late Gothic style, which dramatically illustrates the power and wealth of one of the great Mediterranean mercantile cities.".
Behind the current building, there was an earlier one from the 14th century, which was called the Oil Exchange (Llotja de l’Oli, in Valencian, or Lonja del Aceite, in Spanish). It was used not only for trading with oil, but for all kind of business.
Valencia's commercial prosperity reached its peak during the 15th century, and led to the construction of a new building.
The design of the new Lonja of Valencia was derived from a similar structure in the Lonja of Palma de Majorca, built by the architect Guillem Sagrera in 1448. The architect in charge of the new Lonja was Pere Compte (1447–1506), who built the main body of the building - the Trading Hall or Sala de Contractació (in Valencian) - in only fifteen years (1483–1498). So is written in a blue band that runs along all four walls of the Trading Hall, also called Hall of Columns. It proclaims in golden letters the following inscription:
Inclita domus sum annis aedificata quindecim. Gustate et videte concives quoniam bona est negotiatio, quae non agit dolum in lingua, quae jurat proximo et non deficit, quae pecuniam non dedit ad usuram eius. Mercator sic agens divitiis redundabit, et tandem vita fructur aeterna.
According to the local Valencian scholar Joan Francesc Mira, this inscription showed that it was not a necessary to be a Protestant or a foreigner to establish the basis of a good trade; it also showed the union of ethics and economy. Other construction and decoration works lumbered on until 1548, such as the Consolat del Mar (Consulate of the Sea), a Renaissance building adjoined to La Lonja.
During subsequent centuries, La Lonja functioned as a silk exchange. The honesty of its traders is honored by the inscription that runs around the main contract hall.