The Assassin’s Creed: Revelations team managed to recreate an authentic 16th century Constantinople, even though many of the buildings in the game no longer exist.
[A]rt director Raphael Lacoste and mission design director Falko Poiker turned draftsmen. They made a research trip to the city (today’s Istanbul) to collect images that could be turned into computer graphics. The pair documented landmarks such as the 14th-century Galata Tower and sixth-century Hagia Sophia.
“[T]he team… “recreated 16th-century buildings by breaking them down into their architectural elements. They could look at a 1 x 1cm sketch of a building tucked in the corner of a larger drawing and infer what the full-sized version would be like.”