Director Robert ZemeckisThe Walk is an absolute nail-biter, gripping not only because of the event it portrays – Philippe Petit’s harrowing 1974 high wire walk between the twin towers of the World Trade Center – but because it recreates the buildings involved with astonishing realism. It’s impossible to see them and not be reminded of how they were destroyed, never mind the genuine sense of vertigo you feel as Joseph Gordon-Levitt (or depending on the shot, his wire-walking double) crosses the distance. Which makes it all the more interesting that nearly everything in the film’s recreation of 1970s New York, from the streets below to the drapes and furniture in WTC offices, was a visual effect.

As the film’s Oscar campaign proceeds, we’ve got a visual effects reel breaking down some of the film’s more breathtaking scenes to give a sense of how it came together, and you can watch it here. Everything from the face-swap between JGL and his double to the look and feel of 70s New York gets a moment. Pay special attention to the buildings – the VFX team went over tons of documents, including the original blueprints as well as photos from the entire life of the buildings, to get them right.