THE WORLD’S most unique city leaves visitors never knowing which floor they’re on, and has trains running through buildings.

Chongqing, in China, is described as a “planning and engineering aberration”, thanks to the fact that the ground floor of one building could be the 20th floor of another.

“In Chongqing, the ground floor could be on the 1st, 5th, or 10th floor, depending on which side you enter from” one local said.

The city, which has been described as a “planning laboratory”, has been built this way because it is situated amongst steep hills, cliffs and river valleys, where the ground height can suddenly change by hundreds of metres.

Because of this, buildings in Chongqing, which is roughly the size of Austria, often have entrances on several different stories, depending on what level roads have been built on.

Unlike a regular city, where things are built horizontally, roads, transport networks, and pedestrian walkways are all built on top of each other, a bit like a lasagne.

Skyscrapers are often connected to each other using bridges and even rooftop parks, with schools and cultural centres built on upper levels of the city.

Attempting to explain the complexities of the city, which is home to 32 million people, Hugh (@hughchongqing), a resident who offers tours of the city took to Tiktok to give viewers a virtual tour.

“In Chongqing, we never know which floor we’re on”, he said in a video that has racked up over 27 million views.

Starting off in one of the city’s squares, Hugh explained that although it looks like just a ‘normal square’ on ground level, if you walk across the square you end up on a bridge 22 floors up.

However, if you use the lift located on the square, it says you are on the 12th floor.

Hugh took the lift down to the eighth floor, and ended up back on ground level.

The tour guide then entered the building next door, where a sign on the lift told him he was on the 13th floor.

He exited the building from the 13th floor, went in to the building next to it, crossed over a bridge which was suspended high in the air, and then, on the other side of the bridge, ended up back at street level.

Hugh then went in to the next building along, took the lift to the fourth floor, and ended up back on street level again.

The tour guide then showed footage of a train running straight through a building, suspended high in the air.

Finally, he went into another building, took the floor to the 22nd floor, and ended up back on the square again.

Hugh’s video has likely left many people open-mouthed, as it has racked up over 3.2 million likes, and over 20 thousand comments.

TikTokers raced to the video’s comments section, to share their disbelief at the remarkable city.

One person said: “How is this possible?”

A second person said: “How does navigation work there?”

A third added: “Imagine how hard it is to go by Google maps there!”