In addition to slight extensions to Lines 1, 3 and 4, the proposed expansion will create Lines 5 (Ano Liosia – Vyronas), 6 (Melissia – Perama/Piraeus), 7 (Chaidari – Alimos, crossing the Attiki through downtown Athens) and 8 as a partial circle around Athens (Katechaki – Sepolia – Kallithea – Dafni – Pangrati).
Its built-up area is continuous with that of Athens and the neighbouring suburbs Aigaleo, Chaidari, Petroupoli, Ilion and Agioi Anargyroi.