Line 1 is the oldest of the three lines of the Athens Metro, running from Kifissia to Piraeus. The Athens-Piraeus Railway Company (SAP S.A.) first opened the line, between Piraeus and Thiseio, on 27 February 1869. On 4 February 1885 Lavrion Square-Strofyli railway line opened between Attiki Square and Kifissia. These railway lines gradually merged and converted to a rapid-transit system. It was merged into the Athens Metro network upon the opening of Lines 2 and 3 on 28 January 2000.