What should I do if I didn't register in advance?
You can try to arrange it online in a mobile phone right on the spot for the nearest available time interval. If there are no free intervals (this can mainly happen during the New Year holidays), then you can go to the territory around the mosque without registration. The entrance will be directly near the mosque. Unfortunately, in this case it will not be possible to get into the mosque itself but you will be able to see its splendor from the outside.