Basileios Stoa (Greek: βασίλειος στοά), also Basilike Stoa (Greek: βασιλική στοά), both meaning Royal Stoa, was a stoa constructed in Ancient Athens in the 5th century BC. It was located in the northwest corner (known as "the Herms" because of the great number of Herms set up there) of the Athenian Agora.
The Royal Stoa was the headquarters of the King Archon and of the Areios Pagos council (in charge of religious affairs and crime). A statue of Themis (representing Justice) stands in front of the building. Copies of the city laws were kept in the Stoa.
The front of the building was where Socrates met Euthyphro and had the conversation which Plato recreated in his Euthyphro. It was where Socrates was formally charged with impiety by Meletus. Historians believe that the voting for ostracism, a political practice in Athens during the 5th century BC, may have taken place in front of the Royal Stoa.
- Cf. e.g. Tom Garvey, "Stoa," in Oxford Encyclopedia of Ancient Greece and Rome, ed. Michael Gagarin (Oxford: Oxford Univ. Press, 2010)