This project was born through the premise of the Dark Sky Reserve of Alqueva, and the necessity of incorporate both a observatory and a hotel to accommodate the astrologers. After a rigorous analysis of the reserve, I chose this place for its geographical characteristics. First, its isolation from the civilization, second, the relation it has with the watter, and thirth by almost representing a gate for Alqueva. The program was divided in two different parts. The observatory, situated on a promenant position, and taking advantage of the ruins standing there, and the hotel placed near the watter to have a more "ground relationship".