there are too many places to visit in Istanbul.There are museums, mosques and complexes, churches and synagogues, palaces, pavilions, bazaars, the famous Turkish Baths,fortress, statues and monuments, towers and castles. We can go on and on with regards to places to visit there. If you the adventurous types, I'd suggest you go on your own and explore the city. Atleast thats what I did. But its completely upto you. Weather in May is pleasant. I'd suggest you go in the later half of may because that is when the season begins there. Hope this helps.
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