Nice editing. You can read more about it here.
That’s reality–a two ton building facade. No computer generated special effects.
Joseph Frank “Buster” Keaton (October 4, 1895 – February 1, 1966) was an American actor, comedian, film director, producer, screenwriter, and stunt performer. He was best known for his silent films, in which his trademark was physical comedy with a consistently stoic, deadpan expression, earning him the nickname “The Great Stone Face.” Critic Roger Ebert wrote of Keaton’s “extraordinary period from 1920 to 1929, [when] he worked without interruption on a series of films that make him, arguably, the greatest actor–director in the history of the movies”. His career declined afterward with a dispiriting loss of his artistic independence when he was hired by Metro-Goldwyn-Mayer and he descended into alcoholism, ruining his family life. He recovered in the 1940s, remarried, and revived his career to a degree as an honored comic performer for the rest of his life, earning an Academy Honorary Award in 1959.
Many of Keaton’s films from the 1920s, such as Sherlock Jr. (1924), The General (1926), and The Cameraman (1928), remain highly regarded, with the second of these three widely viewed as his masterpiece. Among its strongest admirers was Orson Welles, who stated that The General was cinema’s highest achievement in comedy, and perhaps the greatest film ever made. Keaton was recognized as the seventh-greatest film director by Entertainment Weekly, and in 1999, the American Film Institute ranked him the 21st greatest male star of classic Hollywood cinema.