The cheapest and most efficient way to get around Istanbul is definitely by public transportation. We bought the InstanbulKart (Rechargeable Transport pass) and used it to get to our hotel in the city centre. The hotel (Holiday Inn Istanbul City) was just a minute's walk from the tram stop which was Pazartekke. The tram can be really crowded during working hours, but we survived!
It was already 4 pm when we checked in and almost sunset. After freshening up, we hopped onto the tram and headed towards Sultanahmet to see the gorgeous Blue Mosque. By then, it was dark. We ended up taking some night shots of the Mosque and tasting delicious Turkish ice cream on the way. I cannot recall the exact name of the ice cream shop but its right next to the Blue Mosque and is a must try!
Our dinner that day was the popular "Balik Ekmek" also know as fish sandwich, available in a number of little food joints under the Galata Bridge. A bun loaded with a large chunk of grilled Mackerel and salads ? Hell yeah!