Birmingham experienced rapid economic growth in the 1820s and by 1830 was sending one thousand tons of goods every week by canal to London.After the success of the Liverpool & Manchester Railway, the business community therefore contemplated their own railway. George Stephenson advised them on the most appropriate route and recommended the appointment of his son, Robert Stephenson, as Chief Engineer in 1833.

The London & Birmingham Railway Company paid Stephenson £1,500 a year to build what was the first railway into London. The 180 km. (112 mile) long London to Birmingham line took 20,000 men and nearly five years to build. The total cost of building the railway was £5,500,000 (£30,000 a km). The railway was opened in stages and finally completed on 17 September 1838. The line started at Birmingham's Curzon Street Station and finished at Euston Station in London. As the Grand Junction Railway had been finished in July 1837, the four major cities in England, London, Birmingham, Manchester and Liverpool were now linked together.

In 1846 the L&BR merged with the Grand Junction Railway and the Manchester and Birmingham Railway to form the London and North Western Railway, which in turn was later absorbed into the London Midland and Scottish Railway, before finally passing into the hands of the nationalised British Rail in 1948 to become part of the West Coast Main Line as it is known today. The major change to the line during this period was electrification, which was carried out during the mid 1960s as part of BR's Modernisation Plan.

Neither of the L&BR's original termini, both designed by Philip Hardwick, has survived in its original form. Curzon Street station in Birmingham closed to passenger traffic in 1854 (the original entrance building remains) when it was replaced by New Street station and the original Euston station in London was demolished in 1962 to make way for the present structure which opened in 1968. However, the roundhouse at Camden has survived intact and is one of the first examples of such structures in the world.

The Roundhouse was built in 1847 as a turntable engine shed or roundhouse. The architects were Robert Stephenson and Robert B Dockray; the builder was Branson & Gwyther. Roundhouses are large, circular or semicircular structures that were traditionally located surrounding or adjacent to a turntable, which offered access when the building was used for repair facilities or for storage of steam locomotives.

Early steam locomotives normally travelled forwards only; although reverse operations capabilities were soon built into locomotive mechanisms, the controls were normally optimized for forward travel, and the locomotives often could not operate as well in reverse. A turntable allowed a locomotive or other rolling stock to be turned around for the return journey - steam locomotives of the time could not run safely in reverse, as their tenders obscured the drivers' view, and the turntable allowed engines to be turned round to point in the forward direction. The design also allowed engines to be kept under cover in a number of radial sidings within the shed.

The Grade II listedbuilding is regarded as a notable example of mid-19th century railway architecture. The original building, 48 m. (157 ft) in diameter, is constructed in yellow brick and is distinctive for its unusual circular shape and pointed roof. The conical slate roof has a central smoke louvre (now glazed) and is supported by twenty four cast-iron Doric columns - arranged around the original locomotive spaces - and a framework of curved ribs. A central 12 m. (41 ft) turntable served 23 stalls for locomotives. The interior has original flooring and parts of the turntable and fragments of early railway lines.

Within twenty years of opening, locomotives became too large for the facilities to handle, and the Roundhouse underwent a number of changes of use. For many years it was a gin store for the firm of W & A Gilbey Ltd until it fell into disuse shortly before the Second Eorld War. It re-opened in 1966 as an arts venue, when the playwright Arnold Wesker established the theatre company 'Centre 42' in the building. The then owners, the Greater London Council, handed control to Camden Council in 1983 when Centre 42 ran out of funds, and the building remained unused until local resident Sir Torquil Norman bought the Roundhouse in 1996 for £6m and spent ten years raising a further £27m to turn the derelict engine shed into a state-of-the-art concert venue and added an educational wing for the performing arts.

The renovation was supported with conservation advice and funding from English Heritage and with grants from the Heritage Lottery Fund and the Arts Council England. The project included the addition of seven layers of sound-proofing to the roof, re-instating the glazed roof-lights, and added the steel and glass New Wing which curves around the north side of the main building to house the box office, bar and cafe, and an art gallery foyer and offices.

See also entries for Barrow Hill Roundhouse and Derby Roundhouse.