Do I need a transit visa at Istanbul Airport to visit the city of Istanbul. I am a Bangladeshi citizen and booked Turkish Airline flight to Russia. Transit period 12 hours in Istanbul. If need transit visa, then how much does it cost?
You will only need a visa if you plan to visit Istanbul. If you are staying in the transit area, then you do not need a visa. From the Turkish Ministry of Foreign Affairs FAQ Page:
Question: I will be flying to Europe. I know that our aircraft will land in İstanbul. I am not planning to leave the transit lounge. Do I need to get transit visa?
Answer: If you will not leave the transit lounge at the airport you are not required to have transit visa. Otherwise, you have to make visa application to the nearest Turkish Representation. Contact information of the said missions can be reached through www.mfa.gov.tr (Ministry/Turkish Representations).
However, if you want to visit Istanbul, then you will need a visa:
Bangladeshi nationals holding diplomatic and official/service passport are exempted from visa for their travels up to 90 days. Ordinary passport holders are required to have visa. These passport holders with a valid Schengen or OECD member's visa or residence permit may get their single entry e-Visas valid for one month e-Visas via the website www.evisa.gov.tr, provided that they meet certain conditions.