The fortifications of Frankfurt were a system of military defences of the German city of Frankfurt am Main which existed from the Middle Ages into the 19th century. Around 1000 the first city wall was built. It enclosed the area of what is now the Königspfalz in modern Frankfurt. In the twelfth century the settlement expanded into what is now Altstadt. For its protection an additional wall, the Staufenmauer, was erected. Starting in 1333, the Neustadt suburb developed north of the Altstadt and was encompassed by an additional wall with five gates. In the fifteenth century, a "landwehr border" was created around the entire territory of the Free City of Frankfurt. Beginning in 1628, the medieval city wall was developed to form a bastion fortress under the municipal architect Johann Dilich.