We got a taxi to Taksim square, making sure we asked how much approximately even though the taxi was metered. If your a tourist most hotels, taxis and tourist restaurants quote prices in euro but the currency is Turkish lira and they will let you pay in either. I made sure I had a currency converter app on my phone and always double checked it. I also made sure when I was haggling with vendors to clarify if the price was euro or lira. The official language is Turkish, sounded like German+Russian to me. Most Turks spoke some English tho it was limited.
We had 2.5 days in Istanbul getting in late around 8pm to the hotel Feronya we decided to relax and eat and make an early day of it tomorrow. Make sure if you go you bring rain gear as sure enough it was drizzling when we started out and got worse as the day wore on. We did not have rain gear with us and I bought a cheap umbrella for about 5 dollars to make do. I recall the Dollar Tree in the states has a 2 pk of rain ponchos for 1 dollar, that would have been perfect had I thought to bring any. If you Google things to do in Turkey you can find a guide that will tell you places to go and the approx time it will take to go thru it.We started off with Topaki Palace and paid extra to see the Harem rooms. Its a huge place and took about 2 hours to go thru it. Next to that was Hagia Sophia and the Blue Mosque