What is the name of that big market where you can find anything and everything? And where is it exactly?

I think you asked for "The Grand Bazaar" ("Kapalı Çarşı" in Turkish). Although The Grand Bazaar have a couple of gates, the most easy way to reach there, from Beyazıt - Grand Bazaar Tramway Station.

I think you asked for "The Grand Bazaar" ("Kapalı Çarşı" in Turkish). Although The Grand Bazaar have a couple of gates, the most easy way to reach there, from Beyazıt - Grand Bazaar Tramway Station.