Late antiquity and the Alamannic period

The fort on the Lindenhof

The third century brought the northern provinces of the Empire into a prolonged crisis. After the abandonment of the frontier east of the Rhine around 260, the region between Lake Constance and the Jura became once more a frontier zone, exposed to raids by Alamannic groups from across the Rhine.¹ Turicum responded, like many settlements in the region, by withdrawing to a defensible position. On the summit of the Lindenhof a fort was built. The Historisches Lexikon der Schweiz dates it to the early fourth century and notes that it provided a refuge for the civilian population. The city archaeology service speaks of a castellum equipped with towers, built in response to the threats of the third and fourth centuries.² The dating is debated, with construction attributed variously to the reigns of Diocletian, Constantine I or Valentinian I. The enclosure covered some 4,500 square metres and was defended by a wall about two metres thick with up to ten towers.³

The fort was small by any standard, but its long-term importance was considerable. The walls of the castellum shaped the Lindenhof plateau, and later medieval building on the hill followed their line. The city archaeology service observes that these defensive walls later supported the development of the medieval town.⁴ Excavations by Emil Vogt in 1937 and 1938, carried out with the labour of unemployed workers during the Depression, and further campaigns in 2008 and 2020, have revealed parts of the late Roman wall. In 2020 the wall was examined again at a depth of five metres at the western edge of the terrace, after a gap of thirty-two years.⁵ The Kanton’s monograph on Turicum emphasises that the settlement expanded from the mid-first century until the fourth and fifth centuries and that by the mid-fourth century its inhabitants withdrew into the fortress on the Lindenhof in unstable times.⁶

The fort marks a change in the character of the place. The open, commercially oriented vicus gave way to a fortified refuge whose primary purpose was security. Trade did not cease, as the votive coins deposited in the small circular cult building into the fourth century suggest, but the scale of exchange shrank with the contraction of the imperial economy. Around 401–402 CE the Roman general Stilicho withdrew troops from the Rhine frontier to defend Italy against the Visigoths.⁷ With that withdrawal the fiscal apparatus which had given Turicum its raison d’être as a customs post also lapsed. No evidence suggests that the quadragesima was collected at the Limmat after the early fifth century.

Alamanni and Romans

The traditional narrative spoke of a violent Alamannic conquest that wiped out the Roman population. Current research paints a more gradual and more differentiated picture. At the level of the canton, the Historisches Lexikon der Schweiz notes that settlement by Alamannic population groups, as evidenced by grave finds, set in only in the seventh century. The subsequent spread of settlement can be traced through place names ending in -ikon (seventh to eighth centuries) and -wil (roughly eighth to ninth centuries).⁸ In the town itself, a romanised population appears to have persisted, as sixth-century burials at the Bäckerstrasse indicate.⁹ Popular local histories describe early medieval settlers who used the Roman street network but built in timber in the vicinity of the old stone structures, and graves of the period have been found near St. Peter, where a cemetery with a chapel occupied the hill.¹⁰

While the Lindenhof retained a function as a protected site, the place name also survived: Turicum became, in the medieval sources, Turegum or Thuregum and, in the vernacular, Zürich. The survival of the name is itself a small piece of evidence for continuity. Place names generally persist where there is some continuity of population able to transmit them. The Latin name of Zurich was carried from the Roman period into the Alamannic and Frankish world without interruption.¹¹

Christianity reached the region in late antiquity. According to the Historisches Lexikon, the area passed around 600 CE from the diocese of Avenches/Windisch into the newly established diocese of Constance, to which Zurich would belong until the Reformation.¹² Of lasting importance was the cult of the martyrs Felix and Regula. According to the legend, recorded in its developed form only in the Carolingian period, the siblings were members of the Theban Legion who had fled from Agaunum (Saint-Maurice) and were executed in Zurich on an island in the Limmat, the site of the later Wasserkirche. After their execution they carried their severed heads up the slope to the place where they wished to be buried, on the right bank, where the Grossmünster now stands.¹³ Archaeology confirms that the Grossmünster was built on the site of a Roman burial ground, which lends a certain plausibility to the tradition of an early Christian cult at a grave on this spot.¹⁴

The cult was of more than religious significance. Because relics attracted pilgrims, donations and royal patronage, the rivalry between the two churches that claimed the saints would structure the topography and politics of medieval Zurich. The geographical link between Agaunum and Turicum in the legend, whether historical or not, is suggestive. Saint-Maurice, the other Swiss customs station of the Gallic duty, was also the site of the most famous martyr cult of the region. Religious and fiscal geography often coincided, since both followed the main routes of communication.

Notes

1. “Limesfall”, Wikipedia (German), https://de.wikipedia.org/wiki/Limesfall, dating the de facto abandonment of the Decumate lands and the withdrawal of the Roman military frontier to the Rhine and the Danube to the years from 259/260 onwards. ↩
2. HLS, “Zürich (Gemeinde)”, section on the Roman period (Andreas Motschi), https://hls-dhs-dss.ch/de/articles/000171/2015-01-25/; Stadt Zürich, Archäologie, “Turicum II”, https://www.stadt-zuerich.ch/de/stadtleben/stadtportraet/zuerichs-geschichte/archaeologie/stadt/auswertungen-themen/turicum-2.html. ↩
3. “Kastell Zürich”, Wikipedia (German), https://de.wikipedia.org/wiki/Kastell_Z%C3%BCrich, which gives the possible attributions (Diocletian, Constantine I, Valentinian I), the area of about 4,500 m², the wall thickness of about two metres and up to ten towers. These dimensions rest on partial excavation, chiefly of the north-eastern foundations. ↩
4. Stadt Zürich, Archäologie, “Turicum II”, https://www.stadt-zuerich.ch/de/stadtleben/stadtportraet/zuerichs-geschichte/archaeologie/stadt/auswertungen-themen/turicum-2.html. ↩
5. Stadt Zürich, Archäologie, “Lindenhof”, https://www.stadt-zuerich.ch/de/stadtleben/stadtportraet/zuerichs-geschichte/archaeologie/stadt/ausgrabungen-bauuntersuchungen/lindenhof.html. ↩
6. Kanton Zürich, press release “Turicum: eine römische Hafenstadt und Zollstation” (February 2021), https://www.zh.ch/de/news-uebersicht/medienmitteilungen/2021/02/turicum-eine-roemische-hafenstadt-und-zollstation.html. ↩
7. “Kastell Zürich”, Wikipedia (German), https://de.wikipedia.org/wiki/Kastell_Z%C3%BCrich, dating the withdrawal of frontier troops by Stilicho to around 402 CE. ↩
8. HLS, “Zürich (Kanton)”, section on the early Middle Ages (Renata Windler), https://hls-dhs-dss.ch/de/articles/007381/2017-08-24/: “Besiedlung durch alemannische Bevölkerungsgruppen setzte aufgrund der Grabfunde erst im 7. Jahrhundert ein.” ↩
9. “Kastell Zürich”, Wikipedia (German), https://de.wikipedia.org/wiki/Kastell_Z%C3%BCrich. ↩
10. “Frühmittelalter”, Zürich damals, http://www.zuerich-damals.ch/fruhmittelalter.html. This is a popular website and is cited here for orientation only. ↩
11. “Turicum”, Wikipedia (German), https://de.wikipedia.org/wiki/Turicum, describing the name Zürich, attested since the early Middle Ages, as the regular development of Turicum after the High German consonant shift, i-umlaut and apocope. The general principle that such survival implies some continuity of population is stated here as an inference. ↩
12. HLS, “Zürich (Kanton)”, section on Christianisation (Renata Windler), https://hls-dhs-dss.ch/de/articles/007381/2017-08-24/. ↩
13. “Geschichte der Stadt Zürich”, Wikipedia (German), https://de.wikipedia.org/wiki/Geschichte_der_Stadt_Z%C3%BCrich, noting that the historical basis of the legend is disputed; HLS, “Grossmünster” (Andreas Meyer), https://hls-dhs-dss.ch/textes/d/D12123.php, on the place where the saints laid down their heads by the Limmat. The connection with the Theban Legion belongs to the traditional legend and is not discussed in these two sources. ↩
14. “Grossmünster”, Wikipedia (English), https://en.wikipedia.org/wiki/Grossm%C3%BCnster, stating that archaeological evidence confirms the presence of a Roman burial ground at the site. ↩

For general information only. This article does not constitute legal or tax advice, does not replace advice on an individual case and creates no lawyer-client relationship. It reflects the legal position as of September 2025.