This famous stairway was built around 1880 by a wealthy man named Abraham Salomon Camondo. It mixes Neo-Baroque and early Art Nouveau styles.
Wikipedia http://en.wikipedia.org/wiki/House_of_Camondo#Camondo_Steps
Address 13 Bereketzade Medresesi Sokak, Beyoğlu 34421, Turkey
Coordinates 41°1'26.281" N 28°58'25.601" E