The Twin Towers were a New York City landmark at 110 stories each. They were completed in 1973. The towers were the centerpieces of the
World Trade Center Complex. They were
the tallest buildings in New York City and, for a brief time, the tallest buildings in the world.
Every day, around 50,000 people went to work at companies with offices inside the towers.
The seven underground levels included stores and a subway station. The South Tower had
an observation deck on the 107th floor, while the North Tower's top floors were home to
Windows on the World, a world-famous restaurant with views extending into New Jersey.
Which sentence best states the main idea of this passage?