The Monitor–Merrimac Memorial Bridge–Tunnel (MMMBT) is the 4.6-mile-long (7.4 km) Hampton Roads crossing for Interstate 664 (I-664) in the southeastern portion of Virginia in the United States.

It is a four-lane bridge–tunnel composed of bridges, trestles, artificial islands, and tunnels under a portion of the Hampton Roads harbor where the mouths of the James, Nansemond, and Elizabeth rivers come together.

The MMMBT cost $400 million to build, and it includes a four-lane tunnel that is 4,800 feet (1,500 m) long, two artificial portal islands, and 3.2 miles (5.1 km) of twin trestle.

The MMMBT is named for the two ironclad warships which engaged in the famous Battle of Hampton Roads on March 8–9, 1862, during the US Civil War.

The site of the battle was within one mile (1.6 km) of the bridge–tunnel structure named by the Commonwealth of Virginia as a memorial.