The Monitor-Merrimac Memorial Bridge-Tunnel MMMBT was completed in 1992, the 4.6 mile-long 7.4 km Hampton Roads crossing for Interstate 664. The tunnel goes under water to allow the ships to move across.
The MMMBT cost $400 million to build, and it includes a four-lane tunnel that is 4,800 feet 1,463 m long, two man-made portal islands, and 3.2 miles 5.1 km of twin trestle.