DANDONG, located at the mouth of the Yalu River and facing the Democratic People's Republic of Korea (DPRK) in northeast China's Liaoning Province, seems no different from any other booming Chinese port city - from afar.

But close up, the city's past becomes visible - a damaged bridge with shell holes and gravestones of unknown soldiers.

It's all about the war: 60 years ago, on June 25, the Korean War (War to Resist US Aggression and Aid Korea) broke out. It soon reached the Yalu River.

Dandong, then named Andong, was at the edge of the battlefield on October 25, 1950. Chinese volunteers (up to 300,000) then marched across the Yalu River from Andong to join the battle. Li Min, 86, then a photographer, recorded the history through his lens.

During the winter of 1951, Li took a now famous photo of Chinese troops crossing the Yalu River. His memory of the afternoon he took the shot remains as clear.

Today the picture is stored in the Dandong Archives.

"It was February and the weather was freezing. The river had iced over and snow was piled up high along the bank. I had no more warm clothes to put on. My fingers were frozen numb. But I didn't care. I tried different angles to shoot. I lay on my stomach, I knelt, I squatted, I stood up. I just wanted to take the best photos," recalls Li.

He could never forget what the soldiers said to him before they marched off.

"They said, 'Comrade Li Min, please take a photo for us. If we come back alive, you just give us the photo; if we don't, you keep it as a memento'." Li says he realized at the time that he was recording history and keeping alive the memory of the soldiers.

He tried to encourage the soldiers by saying they would definitely return home victorious.

"But in my heart, I was not quite sure. The US army was equipped with very modern weapons, but ours were very backward. Who knew whether they would come back alive?" Li says.

"The conditions were very harsh," says Yin Jibo, deputy curator of the Museum of the War to Resist US Aggression and Aid Korea in Dandong. "The temperature was extremely low, sometimes it could drop to minus 40 degrees Celsius. During the second campaign, for example, a lot of soldiers were frozen to death because they did not wear enough clothes."

"What the Chinese soldiers could eat by then was just parched flour with snow ... People could barely swallow it, but they had no other choice," says Yin.

Yin's museum opened to the public in 1993 with more than 20,000 relics and pictures. More than 680,000 people from around the world visited the Museum in 2009 alone.

Ren Shibin from the Inner Mongolia Autonomous Region, is a return visitor to the museum.

"This war made Chinese stand up high in the international community. It is significant in terms of winning victory over a powerful rival and gaining more military experience. It's the first time that China's army, navy and air force joined together in a war," he says.

However, no record or monument has been made for the Chinese soldiers who died in the war. Even the number of dead remains uncertain.

To honor those who died, the Dandong Museum has visited more than 2,000 counties across the country to collect information.

"Our survey updated to 2008 shows that more than 183,000 Chinese volunteers died in the war. It does not include all volunteers who died in the war but it remains the largest so far," says Yin.

The museum staff are now computerizing information of every soldier. "Hopefully, if we can pool enough funds, we can work out a name list, or even build a monument to commemorate their devotion so they can rest in peace," says Yin.

Wang Peizhong has his own way to keep the history in memory. After retiring from the collection department of the museum in 2001, Wang decided to build his own museum to commemorate the war. He wants to tell young people what the war was like. His idea sprang from a conversation with a man he met while he collected war memorabilia.

"I was sometimes asked whether it was of any significance to be so concerned about the war after so many years. Some people thought if not for the war, we could have become well-off a long time ago. I was very upset by those words. I believe it is very important to allow more people to know about the history of the war," Wang says.

Wang sold his apartment in downtown Dandong to raise money for building models of weapons and war figures. He works 12 hours a day and travels around the country to collect model designs.

"History was important in the past, and is also significant for today's economic construction. So I decided to build my own museum before I die to showcase the models of the war. This will be more vivid and attractive to visitors. I will try my best to make these models lifelike," says Wang.

Wang has completed 35 models of figures, weapons and vehicles. He taught himself to make because he thinks they can bring history alive.

In Dandong's Cemetery of Revolutionary Martyrs, director Li Wenjun has been maintaining the graves for many years.

"This is China's first cemetery for martyrs who died in the War to Resist US Aggression and Aid Korea," says Li.

He recalls that the first graves were just piles of earth with the martyrs' names written on a plank with a brush. The planks were later replaced with stones and rebuilt into grand resting places in 2001, with stone coffins lying behind them.

Of the 264 soldiers buried there, Li and his colleagues only managed to collect information about 21 of them. He hopes more people can provide information.

"If we fail to collect as much data as possible, then these people will be buried in the dust of history," Li says.

Sixty years on, Dandong has developed from being on the frontline of the war to becoming a trade in northeast Asia. Around 70 percent of China's trade with the DPRK passes through it. The shell holes in the old bridge and the museums remind people of the war while the orderly traffic flowing across the border shows peace and development.