NABUNKEN NEWS vol.46

Soaring Clay-Brick Retaining Wall

　In the autumn of 2012, the Nara Palace Site Exhibition Hall held a special exhibition entitled “The Underground Shosoin (the Treasure Repository) -- Everything about the First Daigokuden-in (first imperial audience hall complex)”. This exhibition released the compilation of the entire body of results achieved through the excavation investigation that has run for 50 years on the First Daigokuden-in area.

　Here we would like to introduce one of the articles; “Sen”, the bricks produced by burning clay, unearthed from the first imperial audience hall site. In ancient times, these bricks were used mainly for the stylobates and floor of the palace, Buddhist temples and government office buildings. However, it has already been found that for the first imperial audience hall, these bricks were also used as an earth retaining material.

　The first imperial audience hall was constructed on the highest stylobate in the Northern section of the imperial audience hall square. The southern surface of this stylobate was provided with brick walls to enable ground retaining. The clay brick retaining wall possibly stood two meters high, being built with about 25 layers of bricks.

　The clay bricks used for the retaining wall are dark gray, measuring approx. 30 centimeters in length, approx. 15 centimeters in width, and approx. eight centimeters in height. Compared to the JIS standard bricks currently used in modern Japan, which measure 21 centimeters in length, 10 centimeters in width, and six centimeters in height, the ancient clay bricks are about three times larger in volume.

　Although the clay bricks look rather unspectacular when compared to other archaeological materials, when banked up, they can create a tremendous presence. At the autumn special exhibition, a stripped model of the brick wall representing its excavation conditions will be exhibited. Please see it and envisage the ancient solemn elements that only privileged people authorized to enter into the imperial audience hall could observe.

(ISHIDA Yukiko, Department of Imperial Palace Sites Investigations; NAKAGAWA Aya, Department of Planning and Coordination)

Discovered clay-brick retaining walls (Most bricks have gone).