Kings Cross station was built in a hurry. The Great Northern Railway had succeeded against strong opposition in gaining Parliamentary authority to build its main line from Doncaster to London and in 1850 reached a temporary terminus at Maiden Lane. This soon showed signs of weakness and its replacement was urgent.

Kings Cross station opened in 1852 to the design of Lewis Cubitt, whose uncle and cousin were both engaged as engineers by the railway. The design is alleged to be based on the Czar of Russia's riding stables. The station was built on the site of a fever hospital which is also said to have been where Queen Boudicca fought a battle. She is even said to be buried under platform 8.

The ribs of the twin glazed semi-circular roofs were made of timber, a late use of this material for the purpose, and these had to be replaced with iron, the eastern shed in 1866, the western in 1886. In 1972, a one-storey extension designed in-house by British Rail was constructed in front of the station. While the extension was intended to be temporary, it still stands. Many consider the extension unattractive, not the least because it obscures the Grade I-listed fa§ade of the original station.

Prior to the construction of the extension, the station fa§ade had already become hidden behind a small terrace of shops. This extension is scheduled to be demolished, revealing once again the full glory of the Lewis Cubitt architecture, when a new ticket hall and concourse area is built on the station's western side.

In days gone by, part of King's Cross was an intermediate station. On the extreme east of the site was Kings Cross York Road, with suburban trains travelling south from Finsbury Park calling here, then going underground using the York Road curve to join the City Widened Lines to Farringdon, Barbican and Moorgate. In the other direction, trains from Moorgate came off the Widened Lines via the 'Hotel Curve', rising to the main line level on the west side of the main station. Because of the gradient and intensive use by steam engines, this route was notoriously foul smelling and obscured with smoke and steam.