The East and West Chang'an Streets were built as part of the Imperial City of Beijing. East Chang'an Street originally ran from the Left Chang'an Gate (on the east side of the square before Tian'anmen gate) to the Dongdan gate, and West Chang'an Street originally ran from the Right Chang'an Gate (on the west side of the same square) to the Xidan gate. The north side of the square, between the two Chang'an Gates, became a road after 1912 and was named "Zhongshan Road", after Sun Yat-sen. In 1940, the Inner City wall was breached at Jianguomen and Fuxingmen respectively, due east and west of the ends of the East and West Chang'an Street. Streets extending from the ends of the two Chang'an Streets were widened to become Jianguomen Inner and Outer Streets and Fuxingmen Inner and Outer Streets. The two Chang'an Streets thus became part of a major thoroughfare into and out of the Inner City, now considered the "extended" Chang'an Avenue. The two Chang'an Gates were demolished in 1952 to expand Tiananmen Square, after which the two Chang'an Streets and Zhongshan Road were joined together and became known as "Chang'an Avenue".