So you think London, population 8 million, is crowded with the living?
There are many millions more under the soil of a city that has been inhabited for 2,000 years. And London is rapidly running out of places to put them.
Now the city's largest cemetery is trying to persuade Londoners to share a grave with a stranger.
"A lot of people say, 'I'm not putting my Dad in a secondhand grave,'" said Gary Burks, superintendent and registrar of the City of London Cemetery, final resting place of close to 1 million Londoners. "You have to deal with that mindset."
The problem is a very British one. Many other European countries regularly reuse old graves after a couple of decades. Britain does not, as a result of Victorian hygiene obsession, piecemeal regulation and national tradition. For many, an Englishman's tomb, like his home, is his castle.
That view is also common in the United States, which like Britain tends to regard graves as eternal and not to be disturbed _ although the U.S. has a lot more space, so the burial crisis is less acute.
In much of Britain, reusing old graves remains illegal, but the City of London cemetery is exploiting a legal loophole that allows graves in the capital with remaining space in them to be reclaimed after 75 years.
Burks points to a handsome marble obelisk carrying the details of the recently departed man buried underneath. The name of a Victorian Londoner interred in the same plot is inscribed on the other side. The monument has simply been turned around for its new user _ whose family, Burks says, got a fancy stone monument for much less than the market price by agreeing to share.
Since a change in the law last year, cemetery staff have begun the even more sensitive process of digging up old remains, reburying them deeper and putting new corpses on top, in what have been dubbed "double-decker" graves. They'll be sold for the same price as the cemetery's regular "lawn" graves _ those in open grassy areas _ or about $3,200.
Burks, a burly man who began working at the cemetery as a groundsman and gravedigger almost 25 years ago, said reusing graves will buy the rapidly filling cemetery six or seven more years of burials.
"We are doing our damnedest to make the cemetery more sustainable," he said.
So far, no other cemeteries have followed City of London in reusing graves. Many Britons have an instinctive resistance to the idea of grave-sharing.
"I don't even want to think about it," said 29-year-old London receptionist Temi Oshinowo. "It's not showing respect. It doesn't matter whether or not the person has been buried for 25 years or 100 years, that is their space and you should give them respect."
Martina Possedoni, a 23-year-old saleswoman, agreed.
"It's like a second home and it's weird to think a stranger is in your home with you," she said.
It's an attitude that frustrates advocates of grave reuse. Julie Rugg of the Cemetery Research Group at the University of York in northern England jokes that Britain's problem is that "we weren't invaded by Napoleon." Countries that adopted the Napoleonic Code have been reusing graves for almost 200 years.
"We just need to get on with reusing graves," Rugg said. "Grave reuse gifts back to us our Victorian cemeteries to use again."
Britain, a crowded island, has long battled to find room for its departed residents. Over the centuries they have been packed into mass graves, tucked into churchyards and laid out in sprawling cemeteries. London is like a layer cake of the dead: Victorian upon Medieval upon Saxon upon Roman.
Construction workers frequently find remains dating back centuries. Workers building venues for the 2012 Olympic Games have unearthed 3,000-year-old Iron Age skeletons as well as Roman and Medieval artifacts.
For centuries Londoners were buried in churches or small churchyard cemeteries, but when the Industrial Revolution brought a population boom, the existing spaces couldn't cope.
Alarmed at the perceived health risks of overflowing graveyards, the government passed laws starting in the Victorian era that banned urban churchyard burials, outlawed exhumation without government permission and established large municipal cemeteries.
Unlike the cramped churchyards of yore, these Victorian cemeteries were green, park-like spaces that soon became tourist attractions as well as final resting places.
London's most famous, Highgate cemetery, attracts thousands of visitors a year to its tilting tombstones, crumbling crypts and the graves of everyone from Karl Marx to "Hitchhiker's Guide to the Galaxy" author Douglas Adams.
Opened in 1856 on the edge of Epping Forest in east London, the City of London Cemetery is the largest municipal graveyard in Europe _ 200 acres of tranquil avenues shaded by chestnut, lime and plane trees. Its residents include Victorian worthies, 1960s-era soccer star Bobby Moore and Catherine Eddowes and Mary Ann Nichols, two victims of Jack the Ripper.
It hosts 1,000 burials and 2,500 cremations a year, but Burks says that if it does not reuse old graves it will soon run out of space.
He and other burial advocates hope the government will take the initiative and overhaul the law, making the reuse of graves _ currently only permitted in London _ a nationwide practice.
The government is in no hurry to do so. Justice Minister Lord Bach told lawmakers earlier this year that while "the case for reusing old graves had been accepted in principle ... this is a sensitive issue that needs to be handled delicately." He said there were no current plans to expand the practice.
Meanwhile, others are looking for alternatives to burial. Cremation has been encouraged by the authorities for a century as a clean, space-saving alternative. It's also much cheaper _ cremation at the City of London Cemetery starts at $440, while the cheapest adult grave is nearly $1,600.
As a result, Britain has one of the world's highest cremation rates _ almost three-quarters of the population chooses to be incinerated rather than interred.
The future-looking are touting resummation, or "flameless cremation," a process that uses an alkaline solution to dissolve bodies. But it is not yet recognized in British law.
Still, many religions _ including Muslims, Jews and some Christian denominations _ strongly favor burial over cremation and the number of Britons who want to be buried remains steady at more than 25 percent.
Burks firmly believes that burial has a future.
"A cemetery like this," he said, looking around at a tranquil scene of grass, trees and marble headstones, "can be used for generations."
Associated Press Writer Rachel Leamon contributed to this report.