During the repairs to the twin pagodas of Shousheng Temple in the late 1980s, it was already known that they were somewhat tilted. Because the pagodas are located on the alluvial fan of the Yellow River formed over hundreds of millions of years, the underground is sandy soil. Experts say the tilt may be caused by the foundation.

　　Built in imitation of Yuchi Jingde's double whips

　　On June 1, entering through the main gate on the south side, the reporter saw a stone stele standing right in the middle of the twin pagodas, inscribed with “Twin Pagodas of Shousheng Temple, Henan Provincial Cultural Relic Protection Unit”. The twin pagodas of Shousheng Temple are Song Dynasty structures.

　　The temple is watched over by 80-year-old Mr. Ran Xiaoshui from Ranjia Village. He said the twin pagodas are 20 meters apart; the east pagoda is four stories and 18 meters high, and the west pagoda is seven stories and 30 meters high. Both are hexagonal buildings without tops.

　　The Annals of Zhongmu County record: “Shousheng Temple is south of the county seat... Twin pagodas were built there, hence it is also called Twin Pagoda Temple.” According to legend, in the early Qing Dynasty, Shousheng Temple had a stone stele recording that the temple was first built in the Tang Dynasty and flourished in the Song Dynasty. At its peak, it had two courtyards, with a main hall, corridors, mountain gate, wells, and a theater stage, and dozens of monks. The temple was rebuilt in successive dynasties and was destroyed in the 1950s. The existing temple site is surrounded by double earthen walls—an inner stockade and an outer stockade. The east wall combines the inner and outer walls, and the south wall has a gate in the middle. The inner stockade is an earthen mound; the existing inner wall is about 130 meters long from north to south and about 95 meters wide from east to west, standing 3 to 4 meters above the surrounding ground. Most valuable is the preservation of the Song Dynasty twin pagodas.

　　“The shape of the pagodas imitates Yuchi Jingde's double whips. Construction was slow; by the early Song Dynasty, this area was frequently raided. At that time, the west pagoda was built to 30 meters and stopped, and the east pagoda was built to 18 meters and stopped. Neither pagoda ever had a top; now when it rains heavily, the rain flows down along the top of the pagodas.” Mr. Ran said there are many stone steles beside the pagodas. Experts from the Zhengzhou Municipal Institute of Cultural Relics and Archaeology have come to conduct archaeological work many times, saying that the temple and twin pagodas underwent repairs and reconstructions during the Song, Yuan, Ming, and Qing dynasties, and eight steles were erected.

　　The tall pagoda has tilted 40 cm

　　“Do you see it leaning?” Mr. Ran pointed at the tall pagoda. The reporter saw that the lower east pagoda stands upright, while the tall west pagoda clearly leans to the northeast.

　　“In 1986, the Henan Provincial Cultural Relics Bureau allocated funds for restoration. At that time, a plumb bob was used to measure, and the center of the pagoda top was 40 cm off from the center of the base (that is, the top deviates from the vertical line).” Mr. Ran said that in 1986 the twin pagodas were designated by the provincial government as a Henan Provincial Cultural Relic Protection Unit.

　　“This tall pagoda must still be tilting. I worry that if it leans too much, it will fall, and that would be a great pity. Can experts straighten the pagoda?”

　　Expert: Long-term observation is needed

　　Chang Tiewei, an ancient architecture expert and director of the engineering department at the Henan Provincial Institute of Cultural Relics and Architecture Protection, introduced that China has the most ancient pagodas in the world, and almost all ancient pagodas tilt to some degree; some lean more than a meter. Because foundations vary in depth, materials differ in texture, and bearing capacity differs, tilting occurs; there are also causes related to underground soil and groundwater flow. “When the twin pagodas of Shousheng Temple were repaired in the late 1980s, I went there too, and we knew then that they were tilted. The pagodas are located exactly on the alluvial fan of the Yellow River formed over hundreds of millions of years; the underground is sandy soil, which may have caused the tilt due to the foundation.”

　　Chang Tiewei said that straightening a leaning pagoda is now an international challenge. The Leaning Tower of Pisa solicited top experts from around the world to correct it, and correcting the twin pagodas of Shousheng Temple is no small project either. At 40 cm, it should not yet be at the critical value for collapse and should not collapse for the time being. The pagoda has stood for over a thousand years without falling, so it is estimated that the geological structure beneath it has become relatively stable. Long-term observation is needed, and then experts should be found to devise a solution.

　　How was the Leaning Tower of Pisa “straightened”?

　　The Leaning Tower of Pisa was built in 1173 and began to tilt during construction. Originally an architectural failure, it became a world architectural wonder by turning misfortune into a blessing. Galileo's free-fall experiment made it even more famous worldwide. But over time, the tilt gradually increased; before it was closed to tourists in 1990, the top had leaned 3.5 meters south. In 1992, the Committee to Save the Leaning Tower of Pisa was established and solicited solutions globally. Finally, an inclined drilling method was used to slowly extract soil from beneath the foundation on the north side, causing the north foundation to settle and the tower's center of gravity to gradually shift northward under gravity. After 11 years of restoration at a cost of about 25 million, the tower was straightened by 44 cm, basically achieving the expected result. Experts believe that, barring irresistible natural factors, the restored Leaning Tower of Pisa will not collapse for 300 years. It was reopened to visitors on December 15, 2001.