San Cristóbal de La Laguna is a city and municipality in the northern part of the island of Tenerife in the Province of Santa Cruz de Tenerife, on the Canary Islands (Spain). The city is the third-most populous city of the archipelago and the second-most populous city of the island. La Laguna's historical center was declared a World Heritage Site by UNESCO in 1999. In 2003 the municipality started an ambitious Urban Plan to renew this area, that was carried out by the firm AUC S.L.