Monograph No. 53



English Summary


Nara National Cultural Properties Research Institute (Nabunken) 1994


Abridged Table of Contents


Chapter 1: Introduction

 Excavations of the Nara Imperial Palace site; previous research related to reconstruction and restoration of the Suzaku-mon

Chapter 2: Suzaku-mon [Scarlet Phoenix Gate] as mentioned in historic sources

 Scarlet Phoenix Gate of the Nara Imperial Palace; function of the gate; structure of the gate; terminologies describing the gate

Chapter 3: Archaeological excavations of the site of the Scarlet Phoenix Gate, Nara

 Imperial Palace site

 Archaeological features and artifacts

Chapter 4: Designing and building a 1:10 scale model of the Scarlet Phoenix Gate

 Sources and materials used for reconstruction; designing and planning individual parts of the model; building up model

Chapter 5: Considerations and examinations of construction materials for physical reconstruction of the gate

 Basic and applied studies of materials gathered

Chapter 6: Pedologic study of the locality of the gate concerning the resiliency of the earth

 Boring the ground of the site; experimental placement of a dead weight on the ground of the site; trial construction of tamped earth foundation platform

Chapter 7: Examination of basic construction methods

 Tamped earth construction; post construction; normal construction

Chapter 8: Examination of the structural assembly methods used during physical reconstruction

 Structural assembly checked against the current legal requirements; structural comparison with still-standing two-story gates; structural reinforcements; model of reinforcement by steel frame

Chapter 9: Physical reconstruction of the foundation platform of the gate

 Proposal and execution

Chapter 10: Mapping out a proposed scheme for reconstruction of the gate

 Re-examination of the plan in response to the adoption of structural reinforcement; structural calculations under the reinforcement plan

Chapter 11: Preparations for the physical reconstruction of the gate and its commencement

 Appendix: Minutes of working group meetings on the investigations into the Scarlet Phoenix Gate, Nara Imperial Palace



 This report summarizes the results of architectural studies of a physical reconstruction of the Suzaku-mon or the Scarlet Phoenix Gate, Nara Imperial Palace (710-784, A.D.), Nara Prefecture. The Nara Imperial Palace was a compound of emperor’s residence and governmental offices of both of the executive and legislative branches. It was approximately 1.30 hectares in area, and enclosed by wall of more than six meters in height. The Scarlet Phoenix Gate was situated at the center of the south end of the palace. It was in front of this gate where foreign guests were received, welcomed, and seen off. Important ceremonies were also held there. The observation that the Scarlet Phoenix Gate, the state hall compound situated to the north of the gate, and the imperial audience hall further to the north all share the same central axis suggests the political importance of this gate.


 In view of the political importance and international status attached to this gate, it is easy to imagine that state-of-the-art technology was applied to its construction in order to “show off” to foreign guests that the Japanese imperial government was civilized and to the commoners in Japan that the central government maintained strong power and authority over the people. In order to investigate the reconstruction of the Scarlet Phoenix Gate, a multi-disciplinary working group became necessary consisting of eight specialists in architectural history, architecture (structures and materials), archaeology, art history, and historiography. This working group has been continuously active since 1964 when the first archaeological excavation was carried out at the site of the gate. Additional excavations took place three times in 1979, 1989, and 1990.


 Owing to the results of the archaeological excavations, the earthen foundation platform of the gate can be reconstructed to be as follows: The plan was 33m (east-west) by 18m (north-south). Although the top of this platform was removed, its height was calculated to be 1.65m which would cover the total height of the base stones on which pillars stood and groups of cobbles supporting and securing the base stones. The top surface of the platform was covered with flat tiles, as in the cases of contemporaneous temple structures still surviving to date.


 Although all the base stones were removed and broken, the exact locality of each of these base stones (and consequently the exact position of each pillar supporting the supra-structure) could be determined owing to the archaeological discoveries of groups of cobbles supporting the base stones underground. On a total of these eighteen large base stones, pillars supporting the supra-structure of the gate stood. The supra-structure of the gate was five bays (east-west) by two bays (north-south). A bay was a space between two columns, which was 5.015 m (or 17 shaku, with one shaku being approximately equal to 2.95 m). The east-west width of the supra-structure was consequently 25.075 m, and the north-south depth of the supra-structure was 10.03m. The area of the plan of the supra-structure turned out to be 251.5 sq.m. Earthen walls of 2.7 m in width at the base were connected to the eastern and western ends of the gate.


 It was assumed to have been necessary to impress viewers with the height of the gate because of the political importance attached to this gate. Accordingly, the gate’ was hypothesized to be of a two-story building with a roof for each story. The first step to reconstruct the supra-structure was to hypothetically determine the height of a major pillar. It was proposed to be 5.31 m or 18 shaku because the use of 17 shaku (the width of a bay) for the height of a single story would give an impression of a building which was too low. Once the height of the major pillars were determined, the sizes of brackets and other structural parts were proportionally calculated, which would give the height of a roof. Consequently, the estimated height for the entire structure from the ground level to the top of the roof turns out to be 21.98 m. The inclination of the roof was determined to be 6.2/10 owing to the comparison with surviving structures contemporaneous to the Scarlet Phoenix Gate. Besides being a storied-structure, other aspects of the supra-structure which were calculated to impress viewers include the use of three-arm brackets and two layers of rafters exposed beneath the roofs. Because of the international status of the gate, it must have shared many features common to palace structures in Tang China.

 Owing to the comparisons with other contemporaneous temple structures which still survive, the wooden parts of the supra-structure were assumed to have been painted red, window frames on the second floor green, and the exposed ends of wooden structures yellow. The roofs of the gate and the walls were covered with rooftiles because of their archaeological discoveries.


 Although we have carefully mapped out a reconstruction scheme, there still remain serious structural deficiencies that the original Scarlet Phoenix Gate had had innately which we must overcome. The supra-structure is supported by a number of pillars which in disproportionately few to the wide area of the plan of the structure. Indeed, 30 other structures contemporaneous to the Scarlet Phoenix Gate have survived to date owing to structural reinforcements added to them in later periods.


 In Japan, such structural reinforcement can be done by two methods: by a steel frame and by additional wooden structures. The former is considered effective, but attachment of steel frames and wooden structures are a difficult issue to be solved. The problem of metal fatigue is another difficulty to be solved, which gives us serious concern about the longevity and durability of a structure. For these reasons, the latter method has been adopted for a reconstruction of the gate as in the case of the Image Hall of Horyu-ji in Nara. The Image Hall was built more than 1300 years ago, and is the oldest surviving wooden structure in the world, and the structure was reinforced by large numbers of lumber applied to parts which were invisible from the outside, such as the back of the ceilings, at the beginning of the seventeenth century.


 It is our sincere hope that our reconstruction scheme is precise and that a reconstructed Scarlet Phoenix Gate will last as long as Horyu-ji once this project is completed.


1994年3月 発行

奈良国立文化財研究所 学報第53冊