The Montsec range, situated in the Catalan pre-Pyrenees, has been recognised for many years to be one of the places with exceptional conditions for astronomical observation thanks to both its weather conditions and its low light pollution. Light pollution measurements made in the last decade showed that a large part of the Montsec area has exceptional conditions of darkness. Moreover, the fact that the effects of the municipalities located in the area are very low ensures both the quality and the preservation of the night sky.
In 2007, within the framework of the International Conference in Defence of the Quality of the Night Sky and the Right to Observe the Stars, held in La Palma, the International Declaration in Defence of the Night Sky and the Right to Starlight, known worldwide as La Palma Declaration or Starlight Declaration, was adopted. The Starlight Certification System, created by the Starlight Foundation with UNESCO's support through the M&B (Man and Biosphere) Programme, appears based on the Starlight Declaration.
At the end of 2012, Montsec and its sky were evaluated through astronomic and tourist audit processes established by the Starlight Foundation in order to be able to certify the suitability of Montsec. The assessment finished at the beginning of 2013. Its conclusion was that 24 municipalities were certified (totally or partially) as a STARLIGHT TOURIST DESTINATION and 11 of them were also certified (totally or partially) as a STARLIGHT RESERVE (excellent skies). The final conclusion of the whole process is that MONTSEC and its sky are one of the best places in the world for astronomical observation and to enjoy the starlight.