Jason, turning Jerusalem into a Polis, also constructed the constituent architectural elements of a Greek city, including a Gymnasium and an Ephebion. Since the earliest day of archaeology in Jerusalem, great efforts have been invested in locating and identifying these buildings, but to no avail. A prime example is the attempt to locate the Acra, the citadel established by Antiochus IV Epiphanes to house the Seleucid garrison in Jerusalem.[27][28]