Alcalá de Henares , meaning Citadel on the river Henares, is a Spanish city whose historical centre is one of UNESCO's World Heritage Sites, and one of the first bishoprics founded in Spain. Located in the Autonomous Community of Madrid, 35 km northeast of the city of Madrid, at an altitude of above sea level, it has a population of around 200,000, the second largest of the region after the Spanish capital itself. The city is generally known simply as "Alcalá", but "de Henares" is often appended to differentiate it from a dozen cities sharing the name Alcalá (from the Arabic word al-qal'a القلعة for fortification or citadel). The Latin name, Complutum, is sometimes used. The city is capital of its namesake region, Comarca de Alcalá.