This is, of course, the holiest Islamic city in the world and is known as the birthplace of the prophet Muhammed. So if you're wondering what to do in Mecca, nearly all the answers are related to Muslim culture and religion.
The most important of the places to visit in Mecca is Kaaba, a cube-shaped building known as the "house of God". This is the end point of the most important religious pilgrimage in Islam. In one corner you'll find a relic, a Black Stone of meteoric origin. For Muslims, this is the most sacred of the things to see in Mecca, and the experience here is truly unforgettable.
But for more Mecca activities, you can visit other holy places. The first is the Masjid al-Haram, the largest mosque in the city of Mecca and the first holy place of Islam. It consists of a central square surrounded by stone walls and in the center of the courtyard is the Kaaba. Another of the important Mecca attractions is the Well of Zamzam. It is believed that Zamzam water has special properties that calm hunger and cure diseases. Traditionally, pilgrims return from their pilgrimage with a bottle of Zamzam water, though lately its cleanliness has been questioned.
And finally, those looking for more stuff to do in Mecca should go to Mina and Mount Arafat. Mina is a small village where the devil is represented on a 26 meter long wall. After Mina, pilgrims head to Mount Arafat, a place for prayer, and another of the essential things to do in Mecca.