Navigable aqueducts (sometimes called
water bridges) are bridge structures that carry
navigable waterway canals over other rivers, valleys, railways or roads. They are primarily distinguished by their size, carrying a larger cross-section of water than most water-supply
aqueducts. Although Roman aqueducts were sometimes used for transport, aqueducts were not generally used until the 17th century when the problems of
summit level canals had been solved and modern canal systems were developed. The 662-metre long
steel Briare aqueduct carrying the
Canal latéral à la Loire over the River
Loire was built in 1896. It was ranked as the longest navigable aqueduct in the world for more than a century, until the
Magdeburg Water Bridge in Germany took the title in the early 21st century.