Updated

Workers using two giant cranes on the 104th floor roof of 1 World Trade Center have installed the first piece of the spire that will make it the tallest building in the Western Hemisphere.

The nearly 70-ton piece was brought to Manhattan last month by barge. It's the heaviest of 18 parts of the spire that will complete the 1,776-foot skyscraper symbolizing America's freedom.

Dozens of construction workers were on hand Tuesday as the massive, round piece of steel slowly descended into its socket.

Below, there's a view of the Statue of Liberty and Ellis Island.