The Epigraphical Museum is unique in Greece and the largest of its kind in the world. It safeguards 13,510, mostly Greek, inscriptions, which cover the period from early historical times to the Late Roman period, primarily in Greece. The museum is housed in the south wing ground floor of the National Archaeological Museum. It comprises an internal and external courtyard (atrium), a lobby, eleven rooms, a large hypostyle Pi-shaped corridor, a gallery, offices, a laboratory for the conservation of inscribed stone monuments and lavatories. Only the courtyards, lobby and four rooms are open to the public; the other premisces are accessible only to researchers and staff.