There are dozens, probably hundreds, of plague pits under the streets and parks of London.
Most of the pits are in the east of London.
Aldgate Underground station
Daniel Defoe, the author of Robinson Crusoe, wrote a book called A Journal of the Plague Year. He said of the Aldgate pit:
A terrible pit it was, and I could not resist my curiosity to go and see it. As near as I may judge, it was about forty feet in length, and about fifteen or sixteen feet broad, and at the time I first looked at it, about nine feet deep; but it was said they dug it near twenty feet deep afterwards in one part of it, till they could go no deeper for the water; for they had, it seems, dug several large pits before this. For though the plague was long a-coming to our parish, yet, when it did come, there was no parish in or about London where it raged with such violence as in the two parishes of Aldgate and Whitechappel.
Artillery Lane, Bishopsgate
The site of a 14th-century plague pit, which itself stands on the site of a 2nd-century Roman burial ground.
Charterhouse Square, Farringdon
The site of a plague pit from the 14th-century "Black Death" outbreak. Twenty-five skeletons were unearthed during excavations for the Crossrail project.
Gower's Walk, Whitechapel
The "pest fields" of Gower's Walk are close to what is now Aldgate East Tube station. Warehouses, since converted to flats, have been built on the site, but, according to Historic UK, the fields were once used to bury thousands of plague dead.
New Street, Bishopsgate
Hand Alley, as it was then known, was near to what is now Liverpool Street station, and is mentioned in Defoe's A Journal of the Plague Year. He writes:
The upper end of Hand Alley in Bishopsgate Street was then a green field, and was taken in particularly for Bishopgate parish, though many of the carts out of the City also brought their dead thither also, particularly out of the parish of St Allhallows on the Wall: this place I cannot mention without much regret.
Pitfield Street, Hoxton
According to Hackney Council, this was a major plague pit during the Great Plague, and the name "Pitfield" is a reference to that.
Scrutton Street, Shoreditch
Holywell Mount in Shoreditch was a burial site for several centuries before becoming a plague pit during the Great Plague. According to Historic UK, some of the ground is still unbuilt-on, and is visible from number 38 Scrutton Street.
Seward Street, Clerkenwell
Seward Street and Mount Mills, not far from the Barbican, is mentioned in Defoe's A Journal of the Plague Year:
A piece of ground beyond Goswell Street, near Mount Mill, being some of the remains of the old lines or fortifications of the city, where abundance were buried promiscuously from the parishes of Aldersgate, Clerkenwell and even out of the city. Thousands of bodies are thought to lie here.
St Dunstan's, Stepney
St Bride's and St Dunstan's parishes were some of the worst hit by the Great Plague. Records show the two parishes struggling to keep up with the awful logistics of collecting and burying the dead, although they managed. Vanessa Harding, in her essay Burial of the plague dead in early modern London, writes of the "the organised collection of corpses and the opening of mass graves". Burials were supposed to be only at night-time, but the contemporary diarist Samuel Pepys writes that so many were dying that the nights were too short.
St John's Church, Scandrett Street
The church took a direct hit from an incendiary bomb during the Blitz, and only the original tower remains: It has since been converted to flats. From those flats you can see the site of the 1665 plague pit, across the road from the old church.
St Paul's Church, Shadwell
The grounds of the church of St Paul's is confirmed as one of at least five plague pits in Stepney. Bodies were thrown into pits here during the Great Plague of 1664 – 1665.
The rest are mainly central, with a few further north, west and south.
Christchurch Gardens, Westminster
Today, Christchurch Gardens is a small and rather beautiful public park, not far from the larger Hyde Park and St James's Park. But in 1665 it was a burial ground for the nearby St Margaret's Church, and as the plague swept London it was designated a plague pit.
Elephant & Castle
There is a depot for Bakerloo line trains near the Elephant & Castle Tube station. As well as the line to the station, there is another line leading from the depot, which out-of-control trains are meant to turn into if they can't stop. Behind the walls of this tunnel, according to Historic UK, there is a plague pit.
Golden Square, Soho
A beautiful square in the centre of Soho, built in the 17th century and possibly designed by Sir Christopher Wren, notable for a statue of George II, and a townhouse frequented by Queen Anne. It's mentioned in Dickens's Nicholas Nickleby and Evelyn Waugh's A Handful of Dust.
Neither book mentions its history. Lord Macaulay, in his 1848 book The History of England from the Accession of James the Second, writes that in 1685, 20 years after the plague, the square still inspired terror:
On the east was a field not to be passed without a shudder by any Londoner of that age. There, as in a place far from the haunts of men, had been dug, twenty years before, when the great plague was raging, a pit into which the dead carts had nightly shot corpses by scores. It was popularly believed that the earth was deeply tainted with infection, and could not be disturbed without imminent risk to human life. No foundations were laid there till two generations had passed without any return of the pestilence, and till the ghastly spot had long been surrounded by buildings.
Islington Green, Islington
The little triangle of grass next to Upper Street, in prime Islington prams-and-independent-coffee-shops territory, appears to have been a plague pit during the Great Plague.
Knightsbridge Green, Knightsbridge
According to Catharine Arnold's book Necropolis: London and its Dead, between Knightsbridge and Kensington the Piccadilly Line has to swerve to avoid "a pit so dense with human remains that it could not be tunnelled through". Historic UK also believes there was a small plague pit in Knightsbridge Green, near Hyde Park. There was a leper colony there which was co-opted as a plague hospital during the 1665 outbreak, and appears to have later become Holy Trinity church, Brompton.
Marshall Street, Soho
Marshall Street, in Soho, not far from Oxford Circus, was once the site of a plague hospital, or "pesthouse". In between Marshall Street and nearby Poland Street was the pit where the dead of the hospital were buried.
St Giles-in-the-Fields, Soho
The first deaths from the Great Plague were recorded in the parish of St Giles. Samuel Pepys, the diarist, wrote of seeing the red crosses on the door which marked plague-hit houses as he walked through the area. The church is still active today, and its website says that "thousands" of plague victims were buried in pits in its grounds.
Vinegar Alley, Walthamstow
Near St Mary's church in the attractive Walthamstow Village area, Vinegar Alley is reputed to be named after the vinegar which was poured into its plague pit to sanitise the bodies.
For loads more information, visit Historic UK's website.