Since metals were strong but expensive, they were rarely used in ancient buildings. During the Tang Dynasty, Empress Wu Zetian built a 50-metre pagoda of cast bronze and iron, called a tianshu, a symbol of state power, in Luoyang. No other metal pagodas of any height, however, appear to have been built before the Tang Dynasty. The oldest extant iron pagodas are the Fast and West Iron Pagodas at Guangxiao Temple in Guangzhou. They are both square structures made during the Southern Han Dynasty (947-950). Another early iron pagoda was the one at Yiwu in Zhejiang Province. Though it is now dilapidated, its refined structure and beautiful sculptures and castings can still be seen. Judging from its statue of Buddha and the style of the decorative patterns, it was built during the early Northern Song Dynasty. After the middle period of the Northern Song Dynasty it became the fashion to build pagodas of cast iron, and the technology of casting reached a new level. Architects and builders could work out almost any complicated structures and decorative patterns they liked if they could make the right kind of casting. The iron pagoda at Jade Spring Temple in Dangyang, Hubei Province, the one at Ganlu Temple (Sweet Dew Temple) in Zhenjiang, Jiangsu Province, and the one at Jining in Shandong Province all represent the most refined architectural works of that time. By the Ming and Qing dynasties a new fashion of building bronze pagodas, more exquisite than iron ones had developed. The bronze pagoda now standing on Mount Emei in Sichuan Province is regarded as representative of the highest level of casting and moulding. The twin bronze pagodas at Xiantong Temple on Mount Wutai, Shanxi Province, are unique in shape.
Because metal is more expensive and heavier than most other building materials, iron and bronze pagodas were usually not so large and tall as brick and wooden pagodas. Generally, metal pagodas averaged 10 to 20 meters high. The best-preserved iron pagoda in China, the one at Jade Spring Temple in Dangyang, is 17.9 meters tall. The iron pagoda at Jining, though said to be 23.8 meters in height, is actually no more than 20 meters if the stone platform at the bottom is not included. The Thousand Buddha Iron Pagoda at Xianyang, Shaanxi Province, built during the Ming Dynasty, is 33 meters tall, perhaps the tallest of its kind in China.
There are also pagodas made of gold, silver, pearls, ivory, enamel, and other materials, which are more expensive. Pagodas made of such valuable materials are usually small and used only for enshrining Buddhist relics or as ornaments in the underground palace or body of a pagoda or in temple halls and royal palaces. A Lamaist pagoda made of gold was once unearthed while repairing the Qianxun Pagoda at Dali. Inside the gold pagoda were silver alms bowls, agate and a smaller gold pagoda. These relics from the Southern Zhao period are exquisitely made and extremely valuable. The Buddhist pagoda of pure gold kept in the Palace Museum of Beijing and the relic pagodas of gold, silver and precious stones kept in many Lamaist temples in Tibet, Qinghai, Gansu and other parts of the country are all priceless works of art from the Ming and Qing dynasties.
Since pagodas made of bronze, iron and other matels are strong and durable, they can last for ages, even though exposed to the air, provided people have not tried to destroy them on purpose. Though a great number of bronze and iron pagodas were built following the Song Dynasty, not many have been preserved. No more than a few dozens bronze or iron pagodas exist today in the whole country. Most pagodas made of such expensive materials were melted down during transition periods in history for one reason or another.
