Laigh Milton Viaduct is a railway viaduct near Laigh Milton mill to the west of Gatehead in East Ayrshire, Scotland, about five miles (eight kilometres) west of Kilmarnock. It is probably the world's earliest surviving railway viaduct on a public railway, and the earliest known survivor of a type of multi-span railway structure subsequently adopted universally. The viaduct was restored in 1995–1996 and is a Category A listed structure since 1982. It bridges the River Irvine which forms the boundary between East Ayrshire and South Ayrshire.