Ludgate Hill is a hill in the City of London, near the old Ludgate, a gate to the City that was taken down, with its attached jail, in 1780. Ludgate Hill is the site of St Paul's Cathedral, traditionally said to have been the site of a Roman temple of the goddess Diana. It is one of the three ancient hills of London, which also include Tower Hill and Cornhill.
Ludgate Hill is also a related street which runs west from St. Paul's Churchyard to Ludgate Circus (built in 1864), and from there becomes Fleet Street. It was formerly a much narrower street called Ludgate Street.
The legendary King Ludd is supposed to have founded the settlement or City of London, Caer-Ludd in the 1st century BCE. It is derived from Ludd-deen or Valley of Ludd. St. Pauls is situated on top of Ludgate Hill in London, the original settlement of Ludd. Below it is the Roman gate of Ludd called Ludgate.
Many small alleys on Ludgate Hill were swept away in the early 1870s to build Ludgate Hill Station between Water Lane and New Bridge Street, a station of the London, Chatham and Dover Railway.
Not far away, in Cannon Street, is the Roman or pre-Roman London Stone (http://www.bbc.co.uk/dna/h2g2/A863309), from which measurements to London have been taken.
LudgateHill— The appearance of this, the western approach to St. Paul’s, has been completely marred by the railway bridge of the London, Chatham, and Dover Railway, which crosses it at its lower end, and destroys the view from Farringdon-circus at its foot.
Some houses recently built near the foot of the hill, on the south side have been thrown back some feet: and it is hoped that eventually the improvement will be carried out throughout the whole length of the street.
The name Ludgate is derived from an old gate- the sixth and principal gate of London, says Stow in his " Survey" - which was taken down in 1760.