A 700-Year-Old Structure: Tulou

I think I saw this in an architecture documentary. It took a year just to dry it out, which explains why it's lasted so long. This is a place called 'Yongding Tulou' in Fujian Province, China. It's an incredibly old, circular earthen building constructed around 1308. To prevent groundwater from constantly seeping up from the ground, our ancestors first built a sturdy foundation wall of gravel and stone, 1 meter high. Plus, they used a clever waterproofing technique, meticulously filling the gaps with a mixture of lime and sand clay. On top of that, they erected an earth wall a whopping 1.8 meters thick, with bamboo pieces densely layered every 30 centimeters in height. The bamboo essentially acted as the rebar used in modern buildings. Aren't our ancestors' wisdom truly astonishing? The real amazing secret of this building lies in 'weight distribution'. It was designed so that the outer circular earthen wall bears the entire load of the building. Thanks to this, even though the ground subsided over time and the internal wooden pillars tilted a staggering 15 degrees, it didn't collapse and has stood strong for 700 years.