List of capitals in the Roman tetrarchy

This post is a list of capitals in the Roman tetrarchy (established 293 AD). There are 4 capitals listed below alphabetically. The modern city is in parentheses. Source: Wikipedia

• Augusta Treverorum (Trier, Germany)
• Mediolanum (Milan, Italy)
• Nicomedia (İzmit, Turkey)
• Sirmium (Sremska Mitrovica, Serbia)