The 5 bridges, which total 12km in length and connect the mainland of Kyushu with the Amakusa Islands, opened in September 1966. Affectionately known as the “Amakusa Pearl Line,” the series of bridges consists of Bridge Number 1 (Amakusa Bridge), Bridge Number 2 (Oyano Bridge), Bridge Number 3 (Nakano Bridge), Bridge Number 4 (Maeshima Bridge) and Bridge Number 5 (Matsushima Bridge). Connecting these islands by bridge was the brain child of Shigehida Mori, who would also go on to play a leading role in the construction of the 5 Amakusa bridges. They have since become regular sightseeing spots, as well as a popular driving route.
(Taken from the "Kumamoto Prefecture tourism site, Nagomi Journey")