The crown jewel of the city and one of the oldest, largest, and holiest sites in the Islamic world, the Umayyad Mosque is an essential stop. Built on a site that has transitioned from an Aramean temple to a Roman Temple of Jupiter – which provides the current massive walls – and then a Christian cathedral, the mosque houses a shrine said to contain the head of John the Baptist. It is a living room for the city; while foreigners gawk at the shimmering 8th-century gold mosaics depicting a lush paradise, locals gather on the vast, polished marble courtyard to chat, let their children run, nap, or simply soak in the silence. Non-Muslim visitors are welcome outside of prayer times but must be modestly dressed; robes are available for bare arms, legs and female heads. Men enter through the main door, women are diverted via the courtyard to the north, and a rope across the complex keeps you separated. It's handy to bring a bag for carrying your shoes around.