Serra do Marão, Mountain range in Trás-os-Montes e Alto Douro, Portugal.

Serra do Marão is a mountain range in Trás-os-Montes e Alto Douro with multiple peaks and rocky terrain. The massif divides several valleys and features mixed woodland and open grassland along its slopes.

Serra do Marão was a natural barrier that held back progress in the Trás-os-Montes interior until the 19th century. From the 1880s the Douro railway line, routed around the range to the south, became the fastest route across it, carrying passengers and goods. The EN15 mountain road changed little, and the IP4 remained accident-prone between Amarante and Vila Real until the A4 and the Marão Tunnel opened in 2016.

Vineyards cover the inhabited southern slopes of the range, and grapes from these hillsides go into Douro wines. Near Campanhó, a small limestone pocket is quarried and spread on fields to correct soil acidity. Ruins of wolfram mines that peaked during the Second World War stand along the mountain.

Several marked trails wind through the massif, starting from different towns and villages in the region. Walking is best in spring through autumn when paths are dry and weather conditions are generally stable.

The summit holds the Marão geodesic marker and the Marão Astronomical Observatory. Lower down, abandoned wolfram (tungsten) mine workings from the Second World War era remain along the range, and a small limestone pocket at Campanhó is quarried to correct soil acidity for farming.