Sometimes it is not easy to distinguish between a cultural and a natural good because they have, at the same time, significant natural and cultural value. That's why we talk about mixed heritage.

In 2021, UNESCO includes 39 mixed properties on the World Heritage list. The list expands every two years with new assets. Mixed heritage has an Outstanding Universal Value that goes beyond borders. Therefore, we must preserve them for future generations. Its degradation or disappearance would be an impoverishment of the heritage of all peoples in the world.

Let's look at some examples of mixed goods:

- Pyrenees, Monte Perdido, on both sides of the border between France and Spain. It is an extraordinary mountainous landscape whose center is the limestone massif of Monte Perdido, with a height of 3,352 meters. This landscape, made up of villages, farms, fields, high pastures and mountain roads, is an invaluable testimony to the past of European society.

- The ancient Mayan city and the protected rainforests of Calakmul, Campeche. Located in the central and southern sector of the Yucatan Peninsula in southern Mexico, the site includes the remains of the important Mayan city of Calakmul, located deep in the tropical jungle of the Mexican lowlands. Calakmul is also home to an important Mesoamerican biodiversity sanctuary.

- The Historic Sanctuary of Machu Picchu, Peru. Its monuments are integrated in a mountainous landscape of spectacular beauty and are a unique example of a long harmonious relationship between human culture and nature.

- Tikal National Park in Guatemala. Located in the heart of the jungle, Tikal is one of the most important sites in the Mayan civilization. It was inhabited from the 6th century to the 10th century. Its ceremonial center includes temples, superb palaces and public squares that were accessed by ramps.

These 4 examples are heritage of all humanity. In other words, although the 4 properties are in Spain, France, Mexico, Peru and Guatemala, they are a Mixed Heritage of all peoples in the world. Therefore, its conservation and care are of vital importance for humanity.