Kreuztal Viaduct, Steel railway bridge in Oberharz am Brocken, Germany.

The Kreuztal Viaduct, also called Krocksteinviadukt, is a 99 m long, nearly 30 m high single-track railway bridge of the Rübelandbahn. It is a Gerberträger bridge with four fields on three intermediate supports, the middle fields spanning 23 to 27 m, crossing the Kreuztal valley and the B 27 about 1 km east of Rübeland.

Construction of this railway bridge began in 1930 and was completed a year later to allow the line through the Harz mountains. It was built as part of a larger railway project meant to open up the region.

The viaduct carries the Rübelandbahn, formerly the Harzbahn, whose Hüttenrode–Rübeland section was rebuilt in 1930/31. The line is single-track, and trains toward Hüttenrode climb at a gradient of 2.85 percent. Immediately beyond the bridge the track enters a tunnel: the 90 m Nebelholztunnel toward Rübeland, the 307 m Krumme Grube toward Hüttenrode.

The bridge sits where the railway climbs steeply through the Harz forest. Visitors can best view it from hiking paths or from the train as they explore the area.

The bridge was built during a time when modern steel construction was still uncommon, displaying skilled engineering from that era. Its construction posed a technical challenge that forced engineers to develop new solutions for the mountainous terrain.