evidence: This tunnel was built through the 4,642-foot (1,415-meter)-tall Serra do Marão, the sixth highest mountain on mainland Portugal. The Marão Tunnel carries the main highway IP4, which is signposted as A4 in that vicinity, through the mountain. (That highway has also been designated as a portion of European route E 82 of the International E-road network running through much of Europe.) The Marão Tunnel now serves as a pivotal link between the cities of Vila Real in the Vila Real District and Amarante in the Porto District. [...] For his part, Mayor Rui Santos of Vila Real talked about how the tunnel removed what had been a formidable impediment to his own city’s ready access to other communities in the region. "This infrastructure ends the mythical barrier of [Serra do] Marão, a barrier that was physical but was also very psychological," he said.