The Sanitarium Lake Bridges Historic District encompasses a pair of stone arch bridges on Carroll County Road 317 (Lake Lucerne Road) in southern Eureka Springs, Arkansas. Built in 1891 by the Eureka Sanitarium Company to provide access to its resort, they are the only known stone arch bridges in the county, and two of a small number of known surviving stone-arch bridges in the entire state. Both bridges are single-span arches fashioned out of cut stone. Marble Bridge, the northern one, has a span of 44 feet (13 m) across a ravine, while the Lake Bridge has a span of 22 feet (6.7 m) over a normally dry creek bed.