Hlubočepské viadukty, Stone viaduct in Hlubočepy, Czech Republic.

Hlubočepské viadukty are two railway bridges on the Prague Semmering line in Hlubočepy. The southeastern viaduct is 115 m long and 23–25 m high, with seven arches and a steel lattice span between the third and fourth piers; the northwestern viaduct, 500 m away, is 92 m long and 20 m high with five arches. Both arches curve longitudinally, so each bridge bends along the line's 180-degree loop.

Both viaducts were built in 1870–1872 for a branch of the Buštěhradská dráha by Wilhelm Ast with the Klein brothers' firm. Freight trains ran from 3 July 1872 and passenger trains from 16 September 1872. The line climbs so steeply that it loops 180 degrees around Hlubočepy, earning the name Prague Semmering.

The line around Hlubočepy is nicknamed the Prague Semmering after Austria's mountain railway between Vienna and Graz, a name it earned from its climb and the loop that turns back more than 180 degrees over the two viaducts. The southeast viaduct has been protected as the Viadukt Buštěhradské dráhy cultural monument, and since 2006 the northwest one belongs to the Soubor věcí Buštěhradské dráhy.

The two viaducts stand 500 m apart: the longer, higher southeast one spans Hlubočepská street and line 173, the northwest one crosses the same street where Prokopské údolí begins. Both are best seen on foot from the street below; the southeast viaduct is partly on a curve, so walk along to see its arches.

Under the south-eastern viaduct three bridges stack above one another: a road bridge over the Dalejský stream, the railway bridge of line 173 over the same stream, and the viaduct itself. The arches also curve lengthwise, so the whole bridge bends along an arc.