Andrew M.
Yelp
I gather by comparing the Google reviews with TripAdvisor and Yelp that Miniaturk is substantially more popular with Turks than with foreigners, but I still think it's worth a visit. First of all, at current exchange rates it's less than $3 (15 TL). Second, I think it's at least as interesting to see how a country portrays itself -- what they choose to highlight and celebrate -- as to see historical sites and whatnot.
Miniaturk is basically what it says on the tin: a bunch of miniature replicas (at 25:1 scale) of some famous buildings and landmarks in Turkey and the former Ottoman territories. You can walk around the whole layout in an hour or so, although we weren't stopping to scan the QR codes at every stop. In addition to the famous Byzantine churches and Ottoman palaces, there are models of the limestone buildings of Merdin, an old Ottoman bridge in the Balkans, and some of the lesser-known masterpieces of the great Ottoman architects like Mimar Sinan.
(Something that struck me as funny was the model of Istanbul's major football stadium. You can put a coin in a machine to make the speakers blare the fight song of your preferred club, which seems like a great way to make money off of fanatics.)
For an attraction that seems to pull a fair number of visitors, Miniaturk is not in great repair. The miniature train that runs between the exhibits wasn't functioning while we were there, and it's also evident that many of the models were really only constructed to be viewed from one angle. And if you're in Istanbul, I hope you'll go see Hagia Sophia and the like in person. But it was still cool to see some of the sites that didn't make it on to our itinerary, as well as some from the parts of the country (e.g. the Southeast) that tourists won't be visiting any time soon.