Rabat (Arabic: الرِّبَاط‎‎, ar-ribāṭ; Moroccan Arabic: الرَّبَاط‎‎, ar-rabāṭ; Berber: ⵕⵕⴱⴰⵟ, Ṛṛbaṭ) is the capital of Morocco and its seventh largest city center with an urban population of approximately 580,000 (2014) and a metropolitan population of over 1.2 million. It is also the capital of the Rabat-Salé-Kénitra administrative region. The city is located on the Atlantic Ocean at the mouth of the river Bou Regreg. On the facing shore of the river lies Salé, the city's main commuter town. Rabat, Temara, and Salé form a conurbation of over 1.8 million people. Silt-related problems have diminished Rabat's role as a port; however, Rabat and Salé still maintain important textile, food processing and construction industries. In addition, tourism and the presence of all foreign embassies in Morocco serve to make Rabat one of the most important cities in the country. Once a reputed corsair haven, Rabat served as one of the many ports in North Africa for the Barbary pirates, who were particularly active from the 16th through the 18th centuries. Rabat is accessible by train through the ONCF system and by plane through the nearby Rabat–Salé Airport. The Moroccan capital was ranked at second place by CNN in its "Top Travel Destinations of 2013." It is one of four Imperial cities of Morocco, and the medina of Rabat is listed as a World Heritage site.