In der Ey / Chienberg, medieval castle ruins

In der Ey (Burg Kienberg in der Ey) is a medieval castle ruin near Olten in the canton of Solothurn, Switzerland. Only faint traces of the walls remain, but the site has a well-documented past and sits beside walking routes above the town.

What is In der Ey?

The castle occupies a rocky knoll at the north-eastern tip of the Hardwald forest, high above the Olten–Aarau railway line, at roughly 47.3598 N, 7.9223 E. Today it is an archaeological site with scattered wall remnants rather than standing towers or rooms.

Who lived here, and what happened to it?

During the 13th and 14th centuries the castle was the residence of the Olten branch of the Lords of Kienberg. According to the sources, the family had lost an earlier seat in 1241, when the Counts of Frohburg destroyed it during a feud, and In der Ey served as their home afterwards. Historians do not know whether a Frohburg fortification already stood here or whether the Kienbergs built it from scratch.

The first written record dates from 1372: a rent owed to the Schönenwerd monastery concerned a forest plot next to the castle, then called "in der Eya". Sources date the destruction of the stronghold to 1376, during the Gugler War. In 1409 the abandoned site (a Burgstall) passed to the town of Olten, and excavations took place in 1891–92.

How do you get there?

From Olten station take bus line 503 to the Meierhof terminus, then walk a short distance along the Seifiweg. The approach is easy, but the ground is wooded and rocky, so wear sturdy shoes.

What should you know before visiting?

• Entry is free and open at all times.
• There is no cafe, toilet or information point on site.
• The ruin is not wheelchair accessible.
• You will see the position of the old stronghold on its rock spur, not a complete castle plan.
• Other ruins lie nearby, including Alt-Wartburg, so In der Ey fits well into a day of castle hopping around Olten.

Frequently asked questions

Is this the same site as Kienberg-Heidegg?

No. Kienberg-Heidegg is a separate ruin near the village of Kienberg in a different district of Solothurn. In der Ey is close to Olten.

Do I have to pay to enter?

No, the ruin is freely accessible at no charge.

Will I see tall walls or a tower?

No. Only sparse wall traces survive on the rock. It suits visitors who enjoy history and quiet woodland rather than a reconstructed castle.

When was the castle destroyed?

In 1376, during the Gugler War. By 1409 the site belonged to the town of Olten.