Often referred to as "ghost towns" or "ruins" a lost city is a settlement that fell into decline, resulting in it's loss of significance to the world at large. Once thriving cities or villages become almost or completely uninhabited thus falling off the map.
Source: Wikipedia
Also known as the Sanzhi UFO houses or Sanzhi pod houses, Sanzhi Pod City was a set of partially constructed, abandoned buildings in the Sanzhi District of Taiwan.
Amaya is a small village in the Sotresgudo municipality of Burgos, Spain.
Al Arish (Arabic: العريش) is an abandoned village in Qatar, located in the municipality of Ash Shamal. It is one mile south-west of the coastal village of Al Khuwayr.
Karakorum (Khalkha Mongolian: Хархорум Kharkhorum) is the lost capital of the Mongol Empire. You can find the city's ruins to the northwest of Kharkhorin, Mongolia.
Sigiriya or Sinhagiri (Tamil: சிகிரியா) is an ancient rock fortress that served as the capital of Kashyapa I during his rule from around 477 – 495 CE, and is listed as a UNESCO World Heritage Site.
A lost city in Colombia's Sierra Nevada de Santa Marta and is believed to have been built in 800CE.
The capital city of the Daorsi, an Illyrian tribe who lived in the area between 300 BC to 50 BC.
Kowloon Walled City was a densely populated enclave that formed in 1898 and was officially demolished April 1994.
The Kangbashi New Area is a vastly underpopulated city district in Inner Mongolia and is considered a modern ghost town by the western .
Teljä was a late Iron Age settlement in the Satakunta province of Finland.
Lyubutsk was a Russian fortress dating back to 1372
L'Anse aux Meadows is the only confirmed Viking settlement in North America, and it can be found on the northernmost tip of the Great Northern Peninsula.
Tulum (Yucatec: Tulu'um) was a walled, port city of the Mayan Empire found on the east coast of the Yucatán Peninsula of Quinta Roo, Mexico.
Chan Chan is an archeological site in the La Libertad region of Trujillo, Peru.
Timgad was a city in the Aures mountains of Algeria.