King's Cross was built as the London hub of the Great Northern Railway and terminus of the East Coast main line. It took its name from the King's Cross area of London, named after a monument to King George IV that was demolished in 1845.
Plans for the station were first made in December 1848 under the direction of George Turnbull, resident engineer for construction of the first twenty miles of the Great Northern Railway out of London. The detailed design was by Lewis Cubitt, and construction took place between 1851–1852 on the site of a fever and smallpox hospital. The main part of the station, which today includes platforms 1 to 8, was opened on October 14th, 1852. It replaced a temporary terminus at Maiden Lane that had opened on August 7th, 1850.
The platforms have been reconfigured several times. Originally there was only one arrival and one departure platform, platforms 1 and 8 respectively, with the space between used for carriage sidings. As suburban traffic grew, additional platforms were added with considerably less grandeur. The suburban station building now containing platforms 9–11 is from that era.
A new platform, numbered 0, was opened in 2010. To the east of platform 1, it created capacity for Network Rail to achieve a phased refurbishment of platforms 1–8 that includes new lifts to a new footbridge between the platforms. By 2013 the entire station was restored and transformed.
A number of famous trains have been associated with King's Cross, such as Flying Scotsman service to Edinburgh, and the Gresley A3 and later streamlined A4 Pacific steam locomotives, which handled express services from the 1930s until the early 1960s. The most famous of these was Mallard, which still holds the world speed record for steam locomotives.
In 1972, a single-story extension designed in-house by British Rail was built on to the front of the station to contain the main passenger concourse and ticket office. Although intended to be temporary, it still stood forty years later, obscuring the Grade I-listed façade of the original station. Before the extension was built, the façade was hidden behind a small terrace of shops. The extension was demolished in late 2012, revealing once again the Lewis Cubitt architecture. In its place, the 75,000 sq ft King's Cross Square was created, which was opened to the public on September 26th, 2013.
On September 10th, 1973, a Provisional IRA bomb exploded in the booking hall at 12:24, causing extensive damage and injuring six people, some seriously. The three lb device was thrown without warning by a youth who escaped into the crowd and was not caught.
The King's Cross fire of 1987, in which thirty-one people died, was at King's Cross St Pancras Underground station.
The station has changed ownership a number of times: firstly the Great Northern Railway, 1852–1923, then the London and North Eastern Railway, 1923–1948, then following nationalisation British Railways, 1948–present.
One day, Gordon, Duck, and Big City Engine were arguing about what the name of the big station at London was. Gordon thought it was King's Cross, while Big City Engine thought it was Euston. Duck thought it was Paddington since he said he used to work there.