Where is the world's highest observation deck?

In Shanghai of course! The highest point for actually looking out on the city is the Shanghai Tower in Pudong which also hosts the worlds highest observation deck .

How busy is Pudong Airport in Shanghai?

In 2017 Pudong was the 9th busiest airport in the world with 70 million passengers, i.e. the population of Thailand, passing through.

Is Shanghai the busiest Metro System in the world?

Not quite, but nearly! Beijing metro has more annual riders, 3.8 billion, compared to Shanghai's 3.5 billion.

Does Shanghai's Subway have the most stations of any city worldwide?

It comes 2nd to New York. New York City Subway has 424 stations compared to Shanghai's 329. Beijing metro has more annual riders, 3.8 billion, compared to Shanghai's 3.5 billion.

Does Shanghai have the world's longest Metro system?

Yes it does, and there's more planned in the coming years also! Shanghai has the worlds longest subway system as of writing at 644 km long, or 400 miles long , but how long is 644km?