half of which were native to the country. The Palmetum of the center at one point held 4,000 specimens of 250 species. The gardens were opened in 1952 and occupy 70 hectares, including the Henri Pittier Library and National Herbarium. Like other areas of the campus, neglect has caused the upkeep of the gardens to suffer. Lack of irrigation and parasitic species has caused plants to die and the beauty of the gardens to deteriorate. Events that have impacted the health of the gardens include the 2010 El Niño drought, the invasion of the Giant African snail, thefts of groundskeeping equipment, electrical blackouts, and other financial issues restricting the care and management of the facilities. According to staff in August 2019, no water had entered the gardens' pipes since the middle of January 2019. A volunteering plan was created to bring in personal water and manually irrigate the plants. Lake Venezuela The Venezuela Lagoon is the largest body of water on the campus, and takes the shape of the country it is named for. By 2018, the lagoon was reported to have lost half its water; the native Santa Cruz (Victoria amazonica) water lilies, which were 8 ft across and strong enough to hold people, had died out. Other lagoons in the gardens are completely dry. Plaza Cubierta and Tierra de nadie complex The Conjunto Central (Central Complex) of the University City houses many academic, administrative, and social buildings, as well as some of the campus's more famous artworks. The Plaza Cubierta is an indoor-outdoor space designed as an "open museum", combining art into the environment and architecture into art, and is considered one of the most important artistic and cultural works of the country. It also connects many different buildings in the Central Complex.:356-358 Villanueva wanted the Plaza Cubierta to be the heart of the campus, the physical and cultural center, being inspired by halls and city center plazas in Europe. It was inaugurated with the attached Aula Magna on 2 March 1954.:359 Buildings connected by the Plaza Cubierta include: the main library, the rectory offices, the Federation of Students Center (students' union), the Aula Magna, the Paraninfo, and the concert hall (Sala de Conciertos). Of these, and all Villanueva's works, the Aula Magna is considered the "consummate example of synthesis".:356 The Plaza Cubierta is noted for having perforated walls, sections of open roof, and a series of ramps