[mengibar10]

There are 5 prayers, before dawn, just after noon, couple of hours after noon, just after sun sets, and couple of hours after sunset. These varies by time of year and times get closer during winter times and far apart during summer time. Each prayer takes about 20-40 minutes most, except the Friday prayer which is probably the most crowded time and is about one and half hours. It replaces noon prayer on Fridays.

The Blue Mosque just across Hagia Sofia Mosque also allow visitors even during the prayers, except probably during the Friday prayer since it is really crowded. I never had the change to attend Friday prayer there so I am not sure, but I did at other times. Tourist are allowed to visit during prayers and even has the opportunity watching the prayer.

I think it will be very similar if not exactly the same manner. No worries about the visitors of any religion or of no religion. You can experience these majestic structures. I recommend Suleymaniye Mosque, which is much larger than then Blue Mosque but not as big as Hagia Sofia. The mosque at Edirne is from the same architect (Sinan [1]) and bigger than Hagia Sofia.

Current Hagia Sofia is actually the 2rd rebuilt of the original structure. Original was like the churches in Europe and more rectangular than this one, and did not have a dome. The last structure had dome initially but collapse couple of times and was rebuilt. The reason that it collapsed each time is due to the rectangular shape of the base and did not have enough support of half and quarter domes around it. Sinan the architect is actually the one succeeded to keep the dome from collapsing.

[1] https://en.wikipedia.org/wiki/Mimar_Sinan