Yes, tavaf is available 24/7 at Mescid-i Haram. Midnight hours offer the least crowds, coolest temperatures, and most intimate spiritual experience.
Yes, Mescid-i Haram is open 24 hours. Late night tavaf, after Isha until Fajr, is widely considered the best time outside of Hac season. Crowds thin significantly, temperatures drop, and the atmosphere of circling the Kabe under the night sky is profoundly moving.
During non-peak seasons, midnight tavaf can be remarkably uncrowded, allowing you to get close to the Kabe and even touch the Hacer-ul Esved. During Ramadan and Hac, even midnight can be crowded, though less so than daytime.
Practical tips: nap after Isha and set an alarm for midnight. Eat a light meal before heading out. Shops near the Haram often stay open late. The tavaf area briefly clears during Tahajjud namaz congregation. Bring a light jacket.