The idea arrived long before the trains. In 1855 Prime Minister Alexandros Mavrokordatos pushed through a law declaring a Piraeus-to-Athens railway a project of public necessity, granting whoever built it decades of operating rights. Nothing happened for twelve years. The contract finally landed in the hands of an English businessman, Edward Pickering, in 1867, and construction of the surface line began that November. The first train ran in 1869, hauled by steam. When a second railway was later built northward toward the mines at Lavrio, Athenians nicknamed its locomotive the Thirio - the Beast - for the noise and smoke it threw across the suburbs. These two lines, the harbor route and the Beast's route, would eventually be stitched together into the single line that survives today.

In 1904 the railway was electrified between Piraeus and Thisio, and the change rewrote how Athens saw it. The clattering, sooty steam engine gave way to clean electric power, and the line earned the name that stuck: the Elektrikos. A grand new Piraeus station opened in 1928, and in 1930 the electrification was extended from Thisio to Omonia, and Prime Minister Eleftherios Venizelos himself inaugurated the underground station at Omonia, in the city's beating commercial heart. The push north was slower, interrupted by the Second World War, but it resumed afterward station by station - Victoria in 1948, Attiki in 1949, a string of Patisia stops through the 1950s. In 1957 the rails finally reached Kifissia, completing the spine the line still follows. For most of its length the Elektrikos runs in open air; only about 3.2 kilometers through the center dive underground.

For most of the twentieth century the Electric simply was the Athens railway - there was nothing else to call it. That changed in 2000, when two brand-new underground lines opened beneath the city ahead of the 2004 Olympics. The old Electric, by far the senior of the network, was renamed Line 1 and given the color green on the map. Yet it kept its independence longer than the title suggested, remaining operationally separate until 2011, when its operator ISAP was folded into the unified company STASY. Ahead of the Olympic Games every one of its stations was renovated, and between 2008 and 2011 the long stretch from Neo Faliro to Kifissia was rebuilt. A new station at Neratziotissa was added so passengers could transfer to the suburban railway running out to the airport.

Line 1 is a working antique that refuses to stand still. It connects Piraeus and Kifissia across central Athens, sharing the 750-volt third-rail system used by the newer lines and meeting Line 3 at Monastiraki and Line 2 at Omonia and Attiki. Some of its rolling stock dates to the 1980s and 1990s, the older five-car trains found nowhere else on the network. Plans run further still: STASY has long proposed pushing the line beyond Kifissia toward Nea Erythrea and the northern fringe of Attica, a scheme that would require rebuilding Kifissia as an underground station. After more than 150 years the Elektrikos remains what it always was - the line Athens grew up around, still carrying the city between its harbor and its hills.