Athens Metro Line 3 (Dimotiko Theatro – Doukissis Plakentias)

First section of Line 3, opened on 28 January 2000 together with Line 2. Elliniko Metro: construction of Line 3 began in November 1992 and the 7 first stations of the Syntagma – Ethniki Amyna section were handed over in January 2000. Length is the station-to-station distance in the Greek Wikipedia station table (Syntagma 14.2 km, Ethniki Amyna 20.0 km from Dimotiko Theatro). The 1991 base-project contract covered Lines 2 and 3 together and no per-line value is recorded here.

Last section of the base project, opened on 22 April 2003 with one new station, Monastiraki. Elliniko Metro describes it as 1.4 km of tunnel and one station; the station-to-station distance in the Greek Wikipedia table is 0.9 km, which is recorded here, and the OpenStreetMap geometry measures 0.85 km between the stations. The delay came from the Church's objections to a route under Mitropoleos Street, after which the alignment moved to Ermou Street (Greek Wikipedia). Construction start is the November 1992 start of Line 3 as a whole (Elliniko Metro), reused here because the section was part of the base project.

Underground extension north-east from Ethniki Amyna with five stations: Holargos, Nomismatokopio, Agia Paraskevi, Chalandri and Doukissis Plakentias. The extension to Chalandri was handed over on 24 July 2004 and Doukissis Plakentias opened on 28 July 2004. Only Chalandri and Doukissis Plakentias opened in 2004: Nomismatokopio opened on 2 September 2009, Holargos on 23 July 2010 and Agia Paraskevi on 30 December 2010 (Greek Wikipedia). Elliniko Metro gives an underground route of 5.9 km up to Doukissis Plakentias station, where trains reach the surface; the station-to-station distance in the Greek Wikipedia table is 5.2 km and is recorded here. Construction start is the December 2000 date in the English Wikipedia history table, which lists it for the whole Ethniki Amyna – Airport extension.

Westward extension from Monastiraki with three new stations: Kerameikos, Eleonas and Egaleo. Construction of Kerameikos was suspended in 1998 and the station later relocated, because of an archaeological dispute (English Wikipedia). Length is the station-to-station distance in the Greek Wikipedia table (Monastiraki 13.3 km, Egaleo 8.9 km from Dimotiko Theatro).

One-station extension west of Egaleo, opened on 14 December 2013. The Greek Wikipedia gives 1.4 km. The English Wikipedia history table lists a January 2007 construction start shared with a Line 2 row, which is not recorded here.

First part of the Piraeus extension, opened on 7 July 2020 with Agia Varvara, Korydallos and Nikaia stations. The 7.6 km, six-station extension from Agia Marina to Dimotiko Theatro was contracted on 1 March 2012; the contract value is not stated on any page read, so no cost is recorded. Delays are attributed to underground caves along the tunnel, the tunnel's proximity to the sea at Piraeus port and COVID-19 (Greek Wikipedia). Length is the station-to-station distance in the Greek Wikipedia table (Agia Marina 7.5 km, Nikaia 3.2 km from Dimotiko Theatro).

Final part of the Piraeus extension, opened on 10 October 2022 with Maniatika, Piraeus and Dimotiko Theatro stations. The original plan had a further station, Evaggelistria, after Dimotiko Theatro; Attiko Metro cancelled it on 10 November 2008 after local objections (English Wikipedia). The contract value is not stated on any page read, so no cost is recorded. Length is the station-to-station distance in the Greek Wikipedia table (Nikaia 3.2 km from Dimotiko Theatro). Construction start is the July 2012 date in the English Wikipedia history table for the Agia Marina – Nikaia row, reused here because the extension was built under one contract.