The Viaduc d'Ormaiztegi or Ormaiztegi Viaduct is a lattice girder viaduct in Ormaiztegi, Spain that was formerly used by a railroad to link a line from Madrid to Irun.

The viaduct was designed by French engineer Alexandre Lavalley, and construction was completed in 1863.

[2] The viaduct was destroyed during the Spanish Civil War and was reconstructed in 1940.

A modern viaduct was built nearby.

To prevent its demolition, it was declared a historical monument, since after more than 130 years, it has been considered a symbol of Ormaiztegi.