The subterranean settlement was discovered in the Nevşehir province of Turkey’s Central Anatolia region, in the historical area of Cappadocia. [...]

the site, located around the Nevşehir hill fort near the city of Kayseri, appears to dwarf all other finds to date. [...]

The agency has already spent 90 million Turkish liras (£25m) on the development project, but the organisation’s head said he did not see the money spent as a loss due to the magnitude of the historical discovery. — independent.co.uk

In 1963, a man in the Nevşehir Province of Turkey knocked down a wall of his home. Behind it, he discovered a mysterious room and soon discovered an intricate tunnel system with additional cave-like rooms. What he had discovered was the ancient Derinkuyu underground city in Turkey — sunnyskyz