From the Wikipedia: Istanbul Sapphire, or Sapphire, is a skyscraper, and as of 2016, the tallest building in Istanbul and Turkey, located in the central business district of Levent. Istanbul Sapphire was the 4th tallest building in Europe when its construction was completed in 2010. It is the country's first ecological skyscraper. Sapphire rises 54 floors above ground level, and boasts an above-ground roof height of 238 meters: the building has an overall structural height of 261 meters including its spire, which is part of the design and not a radio antenna. Designed by Tabanlıoğlu Architects, it is a shopping and luxury residence mixed-use development managed by Kiler GYO.
I took pictures of the construction. In 2016 I visited the completed building, and went up to the observation platform, taking pictures of the surroundings, near and far.
The nearest Metro station (on the M2 line) is 4. Levent.