Wu planned to create a calendar that introduces an ancient pagoda each day, which later changed to a catalog. He invited veteran enthusiasts to co-write the introductions, but found that people's writing styles varied too much.

In the end, Wang Xuebin, now a scholar studying Chinese ancient pagodas in Henan province, became a co-author of the book.

Wang grew up in Ruzhou, a county-level city in Henan province. His interest in ancient pagodas burgeoned when he was young after hearing legends pertaining to an ancient dense-eave pagoda that stands conspicuously on a top of a hill beside the village where his family lived.

After graduating from university, Wang became a journalist, writing stories about ancient relics, including pagodas.

In 2007, he started sharing his visits to those pagodas in his blogs, and met enthusiasts online, including Wu.

Wang says: "I've been fascinated by ancient pagodas for their profound religious meanings, marvelous architectural structure, great artistic values, and their function of filling in missing parts of historical records that have been lost from mainstream narration, but can still be found inscribed at these ancient monuments."

So far, Henan has recorded more than 700 ancient pagodas, but there must be more to be discovered, Wang says, and his goal is to visit all of them.

Like many enthusiasts, he has been organizing text-based and visual materials about the pagodas in the province, and published several academic papers about auspicious pagodas that emerged during the Ming Dynasty (1368-1644) and pagodas in Henan. The two topics are also what he contributes to the new book he co-authored with Wu.

In October, their weighty 960-page tome about Chinese ancient pagodas was released by China Pictorial Press — Youshengzhinian Yidingyao Kande 1,001 Zuo Zhongguo Guta (The 1,001 Chinese Ancient Pagodas You Must See Before You Die), weighing in at about 3 kilograms.

Alongside the ones that have been listed as national treasures, other precious pagodas that have not entered the list are also featured. It is hailed by many experts as the most comprehensive book in this field.

Ji Huailu, professor at the School of Architecture in Tsinghua University, writes in the recommendation that "the book has established relatively complete archives for top-class ancient pagodas existing in China, and is an important achievement in the study of this area".

The book mainly consists of three parts. Wu uses the first 119 pages to talk about the developmental history of pagodas in China.

In the major second part, the authors make brief but concrete introductions to more than 2,000 pagodas at 680 points that are included in different chapters according to their geographical location. Among them, 960 pagodas are presented on individual pages with text and photos, while 1,000 more pagodas are displayed in groups.

"The '1,001' in the title is not an accurate number of the ancient pagodas included in the book," Wu says. "We introduce the pagodas according to the provinces in which they are located, so as to give readers a route guide if they want to visit them."

The book covers all the provinces, municipal cities and autonomous regions on the Chinese mainland.

The last part includes illustrations about special terms of the pagoda structure, an index and a bibliography.