During the Spanish rule, Christian missionary work began and majestic Baroque churches were built in the Philippines in the 16th Century. The churches' exterior walls were decorated with reliefs of tropical plants and Oriental ornamentations. Vivid stained glass windows and religious paintings decorated the interior of these buildings. Many other traces of the long Spanish rule remain in buildings and streets to this day, and these Baroque Churches of the Philippines have been designated as a World Heritage Site in 1993.