The Ecopista do Dão is a walking and cycling trail in the Viseu district of Portugal. At 49 km long, it is the longest ecopath in Portugal. The road follows the route of the old Linha do Dão railway line and runs from the city of Viseu to the Santa Comba Dão train station in the town of Vimieiro. The Linha do Dão was one of the first narrow gauge railways (type: metric gauge, 1000 mm gauge) 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 abandoned ever since. The Ecopista do Dão was developed between 2007 and 2011 by the Intermunicipal Community of Viseu Dão Lafões (in Portuguese: Comunidade Intermunicipal Viseu Dão Lafões), in collaboration with three municipalities: Viseu, Tondela and Santa Comba Dão.

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

Along the route, wooden fences have been placed at various points to protect users. Regularly there are places where you can do gymnastic exercises 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 of the river.