The world is full of lost cities. Quite why some were abandoned remains a mystery, but others are simply the byproduct of man's inhumanity to man.
And we're not talking the stuff of myths and legends like Atlantis or El Dorado.
See also: Ancient lost city discovered in Egypt
In fact, around the world there are lost cities which civilisation has actually re-discovered; but instead of inhabiting them, we're looking to them for a glimpse into our history, hoping to unearth new secrets every day.
We take a look at the top 10 cities you can actually go and visit - and the holiday packages that should be on your radar for a city break of a lifetime.
1. Ephesus, Turkey From £740pp
At its peak in around 200AD this was the third-biggest city in the world, and its widely-spread ruins include some of the finest Greek and Roman architecture, with ornamental gateways, fountains, temples and amphi-theatres.
This erstwhile capital of Asia Minor was originally developed for its harbour, and for its position dominating the eastern Med.
Abandoned: In the 3rd century AD. The port silted up and the Goths sacked the city.
THE DEAL: P&O Cruises' seven-night Greece and Ephesus itinerary from Malta on Oceana includes flights and full board, from £740pp. Find out more at pocruises.com .
2. Mesa Verde, America From £1,169pp
The first inhabitants of North America left their mark throughout the country. Mesa Verde is a former settlement of the Pueblo people.
It was carved out of a cliff face in south-west Colorado, midway between Denver and Las Vegas, and is now a national park.
Today there are nearly 5,000 known archaeological sites in the park, including 600 spectacularly located cliff dwellings, with a variety of ranger-led walks and hiking trails.
Abandoned: In the 14th century when drought and social instability caused the Pueblos to move south.
THE DEAL: A 10-night Native Trails itinerary which includes flights, car hire and accommodation, costs from £1,169pp. Find out more at americaasyoulikeit.com
3. Petra, Jordan From £668pp
This is the Indiana Jones archetype, a rock-cut city standing like a film set in the desert. Down a deserted wadi, turn the corner, and there it rises, the rose-coloured façade of the Treasury emerging from sheer rock, and beyond it a temple, tombs, a monastery and a theatre.
The artistry is one thing, but the setting is enough to make the hairs rise on the back of your neck. Best approached on horseback, at dawn.
Abandoned: In the 7th century AD, caused by earthquakes, loss of water supplies, and the decline of the Nabataean civilisation which built it.
THE DEAL: Intrepid's eight-day Explore Jordan covers Petra, the Dead Sea and Wadi Rum, from £668pp. Flights extra. Find out more at intrepidtravel.com.
4. Angkor Wat, Cambodia From £637pp
It's an iconic image. A giant temple in the jungle, cracked by tree-roots and throttled by creepers. This 500-acre site is one of the largest religious monuments (originally Hindu and then latterly Buddhist) in the world.
It was started by the Khmer in around 800AD, and developed over the centuries into a sprawl of stupas and staircases, covered in friezes of devils, soldiers and dancing girls.
It is so large that it is comparatively easy to relive the magical, mythical moment of re-discovery – it was lost in the jungle until the 1950s – all alone.
Abandoned: 15th century. The rival Thai kingdom got the upper hand over the Khmer, who moved to the coast.
THE DEAL: G Adventures' nine-day Cambodia Experience allows for three days in Angkor Wat. From £620pp, not including flights. Find out more at gadventures.co.uk .
5. Vathia, Greece From £838pp
This is not one of Greece's multitude of classical sites; this one is much more recent and raw. The Mani is an isolated cactus-choked peninsular of the southern Peloponnese which, until 100 years ago, was populated by heavily-armed Maniots, who lived in towers, built to threaten their neighbours.
Theirs was a culture built on vendetta, and the hilltop village of Vathia, with its passive-aggressive skyline, is typical. In 1900 Vathia had population of 1,000; now it is reduced to half a dozen.
Abandoned: Recently. The world opened up, roads and television came in, and Maniots realised that life didn't need to be so tough.
THE DEAL: Sunvil offers seven nights in a self-catering apartment for two people in nearby Kardamili, including flights, from £838pp. Find out more at sunvil.co.uk .
6. Chichén Itzá, Mexico From £1,299pp
Along with Rome and Egypt, the Mayan civilisation of central and southern America was one of extraordinary sophistication in art, architecture and astronomy.
That's particularly evident in Mexico's Chichén Itzá, whose stepped pyramids, temples and columned arcades are worthy of any empire. It even had its own ball game.
This site, along with coastal Tulum, are within easy reach of brilliant winter sun resorts such as Playa del Carmen on the Yucatan peninsular.
Abandoned: 13th century. Drought? In-fighting? Nobody really knows, but when the conquistadors arrived from Spain, Mayan society was gone.
THE DEAL: Kuoni is offering seven nights five star all-inclusive in Playa del Carmen from £1,299pp, including flights. Find out more at kuoni.co.uk .
7. Kuelap, Peru From £4,935pp
Cousin of the more famous – and now extremely congested – Inca city Machu Picchu, Kuelap is older, larger, far quieter and now more easily reached thanks to a spanking new cable car.
It is in the north of Peru, a place of huge waterfalls, mysterious pyramids and spectacled bears (aka Paddington).
Kuelap itself is an intricately-engineered fortress of hand-carved stones, with temples and the sacred rocks, and it was created by the Chachapoyas (Cloud Warriors), about whom even less is known than the Incas.
Abandoned: 16th century. The Cloud People were wiped out by war and disease when the conquistadors arrived.
THE DEAL: Geodyssey offers a 14-day journey of a lifetime to northern Peru, from £4,935pp, not including flights. Find out more at geodyssey.co.uk
8. Oradour sur Glane, France From £80pp
It looks like the backdrop for an online video game, but this is very much the real thing. Prior to WW2I this crumbling skeleton of a town just down the road from Limoges was a pastoral farming community.
In June 1944 it was part of Nazi-occupied France when a Panzer division took terrible revenge for the shooting of an officer by the local Resistance. Oradour was pulverised, and 642 of its inhabitants – mostly women and children – machine-gunned.
It is impossible to walk down its empty streets unmoved.
Abandoned: 1944. The ruins have been left as a memorial, and a new village has been built to the northwest.
THE DEAL: Last Minute packages flights and two nights' accommodation in Limoges from around £80pp. Find out more at lastminute.com .
9. Chernobyl, Ukraine From £59pp
It is the stuff of science fiction, a real-life post-nuclear landscape, and a taste of just what might be to come. Back in 1986 there was a meltdown in the nuclear power plant at Chernobyl, in what is now the Ukraine. Some 64 people died and 300,000 were evacuated from a 30km radius, and a sarcophagus to encase the damaged reactor was hastily built.
The region is still depopulated, but the wildlife has returned, and tours into the exclusion zone comply with all safety regulations.
Abandoned: 1986. Radiation levels mean that the exclusion zone will remain depopulated for at least 180 years.
THE DEAL: A one-day SoloEast tour of Chernobyl starting from Kiev costs £59pp. Find out more at tourkiev.com .
10. Thebes, Egypt From £925pp
Massive temples, giant carved columns, rows of sphinxes and hieroglyphs, it's all here, and it is a great deal older than anything else in this list.
This giant archaeological site now lies within the confines of modern Luxor, on the banks of the Nile, and in 1500BC it may have been the largest city in the world, with 75,000 inhabitants.
See also: Ancient lost city discovered in Egypt
Abandoned: 1st century AD. Pharaonic rivalry and Roman invasion pulled the plug.
THE DEAL: A seven-day all-inclusive Nile cruise on the ms Grand Rose, Grand Sun or Suntimes that starts and finishes in Luxor costs from £925pp, including flights. Find out more at redseaholidays.co.uk.