Amastrianum

thumb|Map of Byzantine Constantinople. The Amastrianum is located near the middle section of the sea walls, northeast of the Eleutherion harbour and near the [[Myrelaion monastery.]] The Amastrianum (, ), also called Forum Amastrianum by modern authors, was a public square () in the city of Constantinople (today's Istanbul). Used also as place for public mutilations and executions, it disappeared completely after the end of the Byzantine Empire.

==Location== The precise location of the square is unknown: in the work De Ceremoniis, written by Emperor Constantine VII Porphyrogenitus (reigned 913–959), the square was located along the southern branch of the Mese odós (the main street of the city), between the Philadelphion and the Forum Bovis, both stations of imperial processions coming from the Great Palace and heading to the western part of the city. Because of that, the Amastrianum should have lain in the valley of the Lycus creek, between the seventh and the third hills of Constantinople, at midway between the modern neighbourhoods of Şehzadebaşı and Aksaray. According to another source, the square lay in a plain zone on the southern slope of the fourth hill of Constantinople, more or less where the modern roads Atatürk Caddesi and Şehzadebaşı Caddesi cross each other. Administratively, it was included in the ninth Regio of the city.