Wei Yunsi has a lot of time on his hands at work.

The keeper of the clock atop Shanghai's Customs House on the Bund makes a daily trip up two sets of spiral staircases to ensure the smooth functioning of the landmark.

That entails climbing up and down 117 stairs.

"The trick to avoid dizziness is to look horizontally instead of vertically - that is, never look down," he said.

"And the good thing about it is that I'm forced to do exercise every day."

The clock was built in 1927 for 250 kilograms of silver by the JB Joyce tower clocks company from the United Kingdom, which also helped build Big Ben in London.

Though his ambitious travel plans include getting a close look at Big Ben, as well as the clock tower on Moscow's Red Square, the 54-year-old has been locked in Shanghai for most of the last two decades.

"I'm the only timekeeper here," he said.

Wei's job responsibilities also include rewinding the clock springs, lubricating the gears and repairing minor damage.

"It's a mechanical clock, so it requires winding every three days," he said.

The 3.17-meter copper minute hand weighs 49 kilograms, while the 2.3-m hour hand measures in at 37.5 kg.

Wei has been the fourth clock keeper of the tower. Modern technology has made his job easier compared with his predecessors.

Wei Yunsi, the keeper of the clock atop Shanghai's Customs House, maintains its machinery. Gao Erqiang / China Daily