Pireos Street (Greek Οδός Πειραιώς) is a main road linking the Greek capital Athens and the port city of Piraeus. From downtown Athens since the 1970s, it is bypassed by Andrea Syngrou and a small highway southward, and aligns nearly to the northeast from the southwest, while aligning directly in downtown Athens. Its length spans 10 km, running nearly 1 km from the centre of Piraeus by the short Athinon-Peiraios Avenue and up to Omonoia Square (where it is signposted as Panagi Tsaldari on the street signs), near Athens' city hall. Major intersections and an interchange include Karaoli Dimitriou Street, Kifissou Avenue, in which the Kifissos River runs through the middle, the Konstantinopouleos Avenue junction, Apostolou Pavlou with Vasileiou tou Megalou, Ermou, Thermopylon, Sofokleous, Deligiorgi and Sokratous Street. The island areas of the road are aligned with trees, and historically the avenue runs over parts of the north wall and ancient road of Phaleron.
The road was first widened in the mid-20th century. Lampposts were placed on each side of the road, but in the 1990s and early-2000s they were removed, and new taller lampposts added in the island area of the road. Between 2000 and 2001, the extension and conversion from main highway to superhighway began, as an interchange was added. During construction while the overpass above the river was added, flooding occurred in July, September and October of 2002, and the avenue was closed due to flooding of the Kifissos, by special metal gates which prevented further inundation of buildings and Pireos Street. This was the last flooding, as following this stage water began to flow underneath the overpass. Construction continued, and the road now runs underneath Kifissou Avenue. Prior to construction, the main road of Kifissou ended at this road, and residential traffic was allowed south of Pireos.