Big Dig is completed.

The project includes the depression of the Central Artery and construction of the Thomas “Tip” O’Neill Tunnel and Ted Williams Tunnel to Logan Airport. It opened to northbound traffic on March 3, 2003, to southbound traffic on December 20, 2003, and the Albany Street ramps opened in 2006. Construction began September 23, 1991. The largest construction project in Boston history, it was originally estimated to cost less than $3 billion dollars, its ultimate cost is some $24 billion.