The Jeita Grotto () is a system of two separate, but interconnected, karstic limestone caves spanning an overall length of nearly . The caves are situated in the Nahr al-Kalb valley within the locality of Jeita, north of the Lebanese capital Beirut. Though inhabited in prehistoric times, the lower cave was not rediscovered until 1836 by Reverend William Thomson; it can only be visited by boat since it channels an underground river that provides fresh drinking water to more than a million Lebanese. In 1958, Lebanese speleologists discovered the upper galleries above the lower cave which have been accommodated with an access tunnel and a series of walkways to enable tourists safe access without disturbing the natural landscape. The upper galleries house the world's largest known stalactite. The galleries are composed of a series of chambers the largest of which peaks at a height of . Aside from being a Lebanese national symbol and a top tourist destination, the Jeita grotto plays an important social, economic and cultural role in the country. It was one of top 14 finalists in the New 7 Wonders of Nature competition. Location The Jeita cave is situated at the center of the western flanks of the Lebanon mountains, more specifically in the Nahr al-Kalb valley, its natural entrance is about above sea level. It's located east of the Mediterranean coastline and north of Beirut within the confines of the municipality of Jeita, in the caza of Keserwan. History Ancient vestiges of a foundry were found in a smaller cave near the Nahr al-Kalb river, suggesting that the cave was used in antiquity to produce swords. The modern discovery of the underground river of Jeita in 1836 is credited to Reverend William Thomson (an American missionary) who ventured some into the cave. Reaching the underground river, he fired a shot from his gun and the resulting echoes convinced him that he had found a cavern of major importance. In 1873 W.J. Maxwell and H.G. Huxley, engineers with the Beirut Water Company, and their friend Reverend Daniel Bliss, president of the Syrian Protestant College (later the American University of Beirut) explored these caverns. In two expeditions carried out in 1873 and 1874, they penetrated into the grotto before finding their progress blocked by an underground waterfall. The waterfall became known as "Hell's Rapids", as the torrents break onto razor sharp rocks. Dr. Bliss, Mr. Maxwell and