A beautiful fortification called the Propylæa guarded the west side of the Acropolis, where only there was no precipice; and there were other splendid buildings—a new open theatre, for the acting of those unrivalled tragedies of the three Athenian poets, and of others which have been lost; a Museum, which did not then mean a collection of curiosities, but a place where the youth might study all the arts sacred to the Muses; a Lyceum for their exercises, and schools for the philosophers.  These schools were generally colonnades of pillars supporting roofs to give shelter from the sun, and under one of these taught the greatest, wisest, and best of all truth-seekers, namely, Socrates.