Dark rain clouds cast shadows on the abandoned factory, making it appear forbidding, even in daytime. Despite being surrounded by new residential buildings, the old coking plant saw no other visitors that day, just a flock of sparrows flying by.

I stood on muddy ground and looked at the vacated building through head-high grass, wondering why I had decided to explore the site in such bad weather.

There was no sign of an entrance to the factory, so all I could do was try to follow a path left by previous visitors.

When I finally found a way into the building, the only sounds I could hear were raindrops hitting leaves, my footsteps and my own breath. On several occasions, I was too nervous to breathe.

Located between the East Fourth Ring Road and East Fifth Ring Road, construction of the Beijing Coking and Chemical Works began in 1958 as a project marking the 10th anniversary of the founding of the People's Republic of China.

The factory was China's largest independent coking plant and a base for coke supplies and exports. It was also equipped with the country's first domestically developed coke oven.

In its heyday, the plant provided more than 14.8 billion cubic meters of commercial gas for the capital, replacing over 20 million metric tons of coal. It also made a huge contribution to environmental protection.

After five decades of service, it was shut down in 2008 because it could no longer meet the changing needs of urban development.

Since then, it has become a "playground" for urban adventurers such as myself.

The area I stepped into appeared to have been where raw materials were dispatched from the plant.

There were still some small piles of coal lying on the ground, but the sleepers for the railway tracks had long gone.

The window panes were either missing or smashed. With the help of my flashlight, through one window frame I could clearly see several abandoned machines awaiting an unknown future.

I stood in front of a ladder, carefully putting my left foot on a rung and looking up to see where it would take me, but after just a few seconds I decided to against going up.

I told myself: "I don't want to fall from a ladder that may collapse at any time and break any bones. I have a marathon race next weekend."

But the longer you stay in such a building, the greater the chance of experiencing hallucinations.

It was as if I could hear the whistles of trains and see them entering and leaving the site. Looking at the huge chimney, smoke appeared to be billowing from it, while walking into a workshop, it seemed that I could greet the workers who were busy with their tasks.

Signs stating "Beware of the trains" and "No smoking" also appeared to suggest that the factory was still operating.

The plant that witnessed the rapid development of society has been abandoned to the power of nature. Just 11 years after closing, it appears to have been rusting away and battered by the wind for a century.

Clearly, the magic of urban exploration is that it allows you to stand in the present and picture the past.