The Havaş shuttle service from Atatürk Airport and Sabiha Gökçen Airport to Taksim departs every 30 minutes. For more information click here. From Taksim Square you can catch a taxi to the Grand Hotel Haliç in Tepebaşı. The hotel address is:
Refik Saydam Cad.
Tepebaşı Bulvarı No:37
From the hotel it’s a fifteen minute walk to RCAC. See map below or click this link for more information.
As an alternative to taking the Havas bus all the way to the last stop at Taksim Square you can request that the bus driver let you off at the traffic lights near the Grand Halic Hotel.
The traffic lights in question are located at a spot near the former site of the American Consulate and the Pera Palas Hotel. If the bus driver is in charitable mood he might even let you off on Refik Saydam Avenue in front of the hotel itself or at the nearest cross road which is Shimal Sokagi or (in English) North Street.