Osaka Castle's Mysterious Giant Stones

One of the most interesting discoveries I made during my visit to Osaka Castle is the special interest of the constructors for giant stones. The wall surrounding the castle includes 5 colossal stones over 100 tons and 15 stones over 50 tons!
And the method of construction, how these giant stones were assembled together, is still a mystery...

What it is known is that the builders managed to reduce the huge weight by thinning the stones - it was recently discovered that the medium thickness of these giant stones is only 1 meter, which is very thin for a stone with such a large surface.

The best example is Tako-ishi, the "Octopus Stone", the largest stone in the Osaka Castle, measuring over 59 square meters in surface area, 108 tons in weight, with a thickness of 70 to 90cm. It is also the most spectacular of them all, because it has an octopus shape on the lower left corner, which gives its name... and it also makes it a point of attraction for visitors.