Vitruvius, De arch. 5.9.1-2 (ca. 30 B.C.):

1. Post scaenam porticus sunt constituendae, uti, cum imbres repentini ludos interpellaverint, habeat populus, quo se recipiat ex theatro, choragiaque laxamentum habeant ad comparandum. Uti sunt porticus Pompeianae, itemque Athenis porticus Eumeniae Patrisque Liberi fanum et exeuntibus e theatro sinistra parte odeum, quod Themistocles columnis lapideis dispositis navium malis et antemnis e spoliis Persicis pertexit (idem autem etiam incensum Mithridatico bello rex Ariobarzanes restituit); Smyrnae Stratoniceum; Trallibus porticus ex utraque parte, ut scaenae, supra stadium; ceterisque civitatibus, quae diligentiores habuerunt architectos, circa theatra sunt porticus et ambulationes. 2. Quae videntur ita oportere conlocari, uti duplices sint habeantque exteriores columnas doricas cum epistyllis et ornamentis ex ratione modulationis perfectas.

1. Behind the stage, colonnades are to be planned so that when the play is interrupted by sudden showers, the audience may have a place of refuge; the colonnades may also furnish room to set up the stage machinery. At Rome there are the Colonnades of Pompey; at Athens there are the Colonnades of Eumenes, the Temple of Bacchus, and as you leave the theater, on the left-hand side there is the Odeum. This Themistocles planned with stone columns and completed with masts and yards from the Persian spoils. It was burnt in the Mithridatic War and King Ariobarzanes restored it. At Smyrna is the Colonnade of Stratonice. At Tralles there are colonnades above the stadium on either side, like those of a theater. In other cities also which have had skillful architects there are colonnades and walks adjoining the theaters. 2. These, it appears, should be so planned that they are double, having Doric columns on the outside finished with architraves and ornaments in due proportion. (F. Granger, trans.)