The Ecopista do Dão is a cycling and walking trail in the Viseu district of Portugal. With its 49 km length, it is the longest ecopista in Portugal. The path follows the route of the former Linha do Dão railway line and runs from the city of Viseu to the Santa Comba Dão train station in the village of Vimieiro. The Linha do Dão was one of the first narrow gauge railways (type: meter gauge, 1000 mm wide) in Portugal. The line was inaugurated on November 25, 1890. Between 1997 and 1999, the rails and sleepers were removed. The stations remained intact and have been neglected ever since. The Ecopista do Dão was developed from 2007 to 2011 by the Intermunicipal Community of Viseu Dão Lafões (Portuguese: Comunidade Intermunicipal Viseu Dão Lafões), in collaboration with three municipalities: Viseu, Tondela and Santa Comba Dão.

The ecopista has a length of 49.2 km and crosses the three municipalities of Viseu, Tondela and Santa Comba Dão. The road surface is completely paved. In each municipality, the path has a different color: red for the route within the municipality of Viseu, green for Tondela and blue for Santa Comba Dão.

Wooden fences have been placed along the route at various places to protect users. There are regularly places where gymnastic exercises can be done with the help of, for example, stretching. In the part of the municipality of Santa Comba Dão, the path follows the Dão river with views over the river.