In 1967 the new International Airport Pudahuel was opened, and, after years of discussion, in 1969 construction began on the Santiago Metro. The first phase ran beneath the western section of the Alameda and was opened in 1975. The Metro would become one of the most prestigious buildings in the city. In the following years it continued to expand, with two perpendicular lines in place by the end of 1978. Building telecommunications infrastructure was also an important development of this period, as reflected in the construction of the Torre Entel, which since its construction in 1975 has become one of the symbols of the capital and the tallest structure in the country for two decades.