In this task you will be given an answer to a question. You need to generate a question. The answer given should be a correct answer for the generated question.
Q: The Chesapeake Bay Bridge -- Tunnel (CBBT) is a 23-mile (37 km) fixed link crossing at the mouth of the Chesapeake Bay in the U.S. state of Virginia. It connects Northampton County on the Delmarva Peninsula with Virginia Beach, which is part of the Hampton Roads metropolitan area. The bridge -- tunnel originally combined 12 miles (19 km) of trestle, two 1-mile-long (1.6 km) tunnels, four artificial islands, four high-level bridges, approximately 2 miles (3.2 km) of causeway, and 5.5 miles (8.9 km) of approach roads -- crossing the Chesapeake Bay and preserving traffic on the Thimble Shoals and Chesapeake shipping channels. It replaced vehicle ferry services that operated from South Hampton Roads and from the Virginia Peninsula from the 1930s. Financed by toll revenue bonds, the bridge -- tunnel was opened on April 15, 1964, and remains one of only ten bridge -- tunnel systems in the world, three of which are located in Hampton Roads, Virginia.
A:
when was the chesapeake bay bridge tunnel completed