신비한사전

Cars and trains that were running on the sea suddenly dip down and disappear into the sea. This was because there was an airport flight path above and a shipping lane for large vessels below, making it impossible to build a bridge either high or low. So, they decided to hide it completely underwater. This undersea tunnel wasn't dug; it was assembled. They built 20 concrete boxes, each 176 meters long, on land and submerged them one by one into a trench on the seabed, fitting them together like a puzzle. They even used the excavated soil to create an artificial island in the middle, so nothing went to waste.

These are gates that normally lie on the seabed and only stand up when the sea level gets dangerously high. Each gate weighs up to 330 tons, and compressed air is used to lift them. When the seawater inside is pushed out by air, the now lighter gate floats up on its own due to buoyancy. If the walls were always standing, ships couldn't pass and the lagoon water wouldn't circulate, so they created walls that only appear when needed. It's like protecting the city while also keeping it breathable. After the storm passes, they refill them with water and lay them back down on the seabed.

Deep beneath Tokyo, 50 meters underground, lies a massive chamber where 59 pillars, each weighing 500 tons, stand in a row. But these pillars aren't holding up the ceiling. They're there to press down and prevent the empty chamber from floating up due to groundwater. With no land to widen rivers and gentle slopes making drainage difficult, engineers decided to hide the floods underground. It's even more astonishing that four pumps can empty a 25-meter swimming pool every second. They stand ready, silently, beneath Tokyo today.

You'd think a breakwater should be sealed tight, but tetrapods have nearly half of their space empty. Instead of blocking waves with force, they let them pass through and dissipate their energy. As water flows in and out, the currents split and collide, gradually weakening the waves. There's also a reason why the four legs are spread out in all directions. When placed, three legs support the base, and the remaining one wedges between adjacent blocks, interlocking like clasped hands. This prevents them from being washed away alone when the waves pull at them.

The idea is to give up designing each shell individually and cut them all from the same sphere. Since the curvature of the sphere's surface is the same everywhere, the components could be mass-produced at a factory. A single sphere with a radius of 75m served as the blueprint for the entire roof.

When the front yard is heated by the sun and the back yard is cooled by the shade, the temperature difference creates a pressure difference, allowing the wind to blow on its own. The Daecheongmaru, open front and back, is precisely this wind path. The empty front yard wasn't due to a lack of decoration, but served as a wind factory.

Instead of building structures strong enough to withstand earthquakes, this concept involves isolating them from the ground entirely. Layers of rubber and steel plates act as supports that absorb all the shaking. This is particularly useful for buildings that cannot afford to stop operating, such as hospitals or power plants.

Since the city was built on a swamp and there wasn't enough depth for sewers, they lifted the entire city. 600 workers operated 6,000 jacks simultaneously, raising one block in five days. What's more surprising is that shops continued to operate as usual during this time, and not a single pane of glass broke.

This is a city where buildings were carved out from red sandstone cliffs, starting from the top. The remaining rock served as a foothold, so there was no need to build separate scaffolding. The way the 40m-high temple suddenly appears after passing through a 3m-wide, 1km-long gorge is truly amazing. The Nabataeans were incredible.

This underground city was made possible by tuff, a rock that is soft when excavated but hardens when exposed to air. Vertical shafts served as ventilation and wells, and the circular stone doors could only be opened from the inside. It's estimated that up to 20,000 people could hide and live there. The idea of building a city downwards, not upwards, is amazing.