There are plenty of stories out there where people are doing some type of home renovation and they find something interesting hidden behind their walls.

It could be notes left from previous owners, colonies of insects, dead bodies, or even a hidden room.

In 1963, however, a man in Turkey found what is likely the most surprising thing possible when he took a sledgehammer to his basement wall – a tunnel that led to an ancient underground city where as many as 20,000 people may have lived.

This underground city is called Derinkuyu, and (fortunately for the homeowner) has been abandoned for many generations.

It is believed that this city first got its start sometime between the 8th and 7th centuries BCE.

In this underground city you would find homes, shops, temples, schools, and even stables. The total area under the ground covers about 445 square kilometers (172 square miles).

There are many entrances to this city, including some that are well concealed to help keep its occupants safe.

There are also ventilation shafts throughout the city to ensure fresh air is able to be brought into the area, allowing people to live underground indefinitely.

The ground in this area is relatively soft, developing from volcanic ash deposits. This made it easier for the original builders to construct the city.

It is likely that this city started with regular people digging out cellars and other underground food storage rooms.

By having rooms underground, the temperatures and humidity were much more consistent, allowing food and drinks to be kept safe longer.

Over time, the area continued to be developed, with significant expansions likely coming during times when the people living in the area were threatened by war or other issues.

Having an underground city like this offers some significant benefits, including staying out of the sight of enemies looking to cause you harm.

You can learn more about this incredible city on this YouTube video:

Nothing you find behind the walls in your home will compete with this incredible discovery.

It might still be cool, though.

If you thought that was interesting, you might like to read about why we should be worried about the leak in the bottom of the ocean.