fortifications

The fortifications of Olten, in the canton of Solothurn, Switzerland, are the surviving traces of the town's defensive walls, which reach back to late antiquity. Olten is one of the places where a Roman outline is still readable in the layout of the old town.

What are the Olten fortifications?

Around 330 AD a small Roman settlement on the Aare was enclosed with a wall and ditch, turning it into a castrum. The wall was about 3.5 metres thick. When a medieval town grew here, its builders did not start from scratch: the 13th-century ring wall was set directly on top of the Roman one. As a result Olten barely expanded beyond the old castrum footprint, and its late-Roman defences show more clearly in the townscape than those of neighbouring Solothurn.

What can you see today?

Sections of the wall on the north and west sides survive. The last stretch standing above ground was pulled down in 1902 near Klosterplatz, next to the former Rittersaal. The Roman ditch had been filled in by the end of antiquity, and a new medieval moat was dug closer to the wall. That moat is gone too, but a lane northwest of the old town is still called Graben, "the moat".

Archaeologists keep finding more. In 2020 a stretch of Roman wall at least 1.8 metres wide came to light inside the Hexenturm. In December 2023, during renovation of the former Lichtspiele cinema, the castrum ditch was uncovered. Together, the finds show the Roman defences extended slightly further south than today's old town.

How do you visit?

This is a walk rather than a single ticketed monument. Start near Klosterplatz and follow the old town's outline, watching for streets that trace the former wall line. Allow about an hour, less if you skip the cafés. Olten is a major rail junction, so arriving by train is easiest; the old town is a short walk from the station across the Aare bridge.

Frequently asked questions

How old are the Olten fortifications?

The oldest wall dates to late antiquity, around 330 AD. The medieval ring wall of the 13th century was built on its foundations.

Does the whole wall survive?

No. Parts of the north and west sides remain. The last section above ground was demolished in 1902.

Is there an entrance fee?

No. You see the traces while walking through the old town; there is no single ticketed entrance.

Are new discoveries still being made?

Yes. New sections of wall and ditch turned up in 2020 and 2023 during building work in the centre.