Tatsuyama stone was formed from hardened volcanic ash
during the Cretaceous period
( one hundred million years ago).
It has been used in large quantities in the construction
of stone walls at Himeji Castle ( a National Treasure ).
In the Meuji and Taisho periods,
and the beginning of the Showa period,
it was put to pratical use as a popular building material.
The stone has been used at the Imperial Hotel,
the Diet building and
in the Imperial Palace's Fukiagegyoen,
to name a few examples.
It is classified into three colors:yellow,blue,and red.