An evening view of Longmen Grottoes crowded with tourists on May 24, 2025.

A researcher from Longmen Grottoes Research Institute collects data with a scanner at a cave on May 12.

A niche statue gathered by the institute is displayed in Chengdu on Aug 20, 2025.

An image niche collected by the institute.

At Longmen Grottoes south of Luoyang city, Henan province, craftsmen carved more than 100,000 statues and more than 2,000 niches on cliff faces more than 1,000 years ago. Through digital technology, preventive conservation and cultural-tourism integration, Longmen Grottoes are gaining renewed vitality.

Near the Cave of Ten Thousand Buddhas stands a statue of Avalokitesvara, with a graceful figure and flowing robes, known by many as "Longmen's most beautiful Guanyin". Ironically, its most striking feature is missing: the section from below the hair bun to above the nose, the part that best conveys the statue's expression, was damaged.

Fortunately, visitors can still admire its grace in the digital world.

Using a mobile phone, visitors can view an augmented-reality reconstruction of the statue, with dignified eyes and a serene countenance. By swiping the screen, they can also view its original colors: warm stone tones on the skin and faint traces of mineral pigments on the robes.

Using historical photographs, 3D scanning, color detection and analysis, and traditional sculptural techniques, the Longmen Grottoes Research Institute has completed the virtual restoration and color reconstruction of the statue.

In late March, the institute officially began collecting digital data on the Lotus Cave. This work goes beyond simple documentation, creating a precise digital archive of the cave.

"The Lotus Cave is one of the representative caves of the Northern Wei Dynasty (386-534) at Longmen Grottoes, boasting rich content and exquisite carvings," said Li Linlin from the Longmen Grottoes Research Institute. The data can support conservation research and scientific studies, and can also be combined with virtual restoration, augmented reality, artificial intelligence and other technologies to recreate the grandeur and delicacy of Longmen's caves, niches and statues in diverse ways, she said.

"Since the launch of the 3D digital project in 2005, the institute has carried out systematic, high-precision data acquisition for key caves. Today, every tiny detail is captured down to the millimeter," said Zhang Guofeng of the institute, while presenting a set of 3D scanning data. Buddha statues have been fully brought into digital space, with clear renderings of robe folds, facial features and rock textures. "Early digital work focused largely on measurement, while today we systematically collect, store and model statue data."

For relics scattered overseas, the team carries out 3D data capture, digitally joins them with surviving sections at the grottoes and produces digital models through 3D printing. This enables "digital reunions" for statues whose heads and bodies were separated.

First carved after Emperor Xiaowen of the Northern Wei moved the imperial capital to Luoyang, Longmen Grottoes are a world-famous UNESCO World Heritage Site and a treasure trove of stone-carving art. To better protect and pass on this gem of Chinese culture, the institute conducts conservation and restoration work, technical research, heritage monitoring and digital preservation. Projects tackling hazards such as water seepage, unstable rock masses and weathering are steadily advancing, gradually forming an overarching conservation framework for the grottoes.

On July 22, the World Internet Conference released its case collection on the digitalization of cultural heritage in 2026. The touring exhibition of data aggregation and 3D printing of damaged and dispersed cultural relics from Longmen Grottoes was included in the collection. The exhibition has toured many regions across China.

Standing before a set of 3D-printed Buddha heads and fragmented statues, one visitor said: "The moment I see them put back together, it feels as if something inside me has been made whole."

At a research and study class themed "bring national treasures home", Li Peijun, an assistant librarian at the Longmen Grottoes Research Institute, screened a short video. In the video, a Bodhisattva head from Longmen that was looted and taken to Japan serves as the narrator. "I have watched over Longmen for more than a thousand years. Sadly, I was chiseled away and stolen. Now I reside in Tokyo, longing to return to my homeland." The touching monologue moved the students, who hoped that national treasures overseas would return home soon.

During the message-writing session, Ma Yuhan, a primary school student from Luoyang, wrote: "They should be telling stories of history in their hometown, yet they are separated by vast mountains and seas. I hope I can do my part to help them come home soon."

Currently, 20 special caves at Longmen Grottoes are open to adults seeking in-depth cultural experiences, with professional researchers and guides leading art-appreciation sessions and academic exchanges. A variety of engaging study-tour programs have also been designed for teenagers.

Walking through Longmen Grottoes today, students on study tours can be seen everywhere. They listen carefully as guides recount the site's history.

The grottoes' international outreach has also achieved initial results. An international communication center for the grottoes was put into use in 2025 and its English website and official accounts were launched on five major overseas social media platforms. A series of short documentaries — Ten Visions of Longmen — has been released for global audiences.