At Makkah’s heart is the expansive Grand Mosque, which can accommodate as many as 4 million worshippers. Its focal point is the Kaaba, the cube swathed in black silk with gold calligraphy at the center. The holiest mosque in Islam, this is where pilgrims perform the Umrah, by donning the appropriate attire and performing prescribed steps like the tawaf (walking around the Kaaba seven times) and strolling between the hills of Safa and Marwa seven times. If you have any questions about the steps, ask your travel agent for a pamphlet or pick up a book before you go.