The Alt-Wartburg ruins were built at the end of the 12th century by the Lords of Ifenthal and destroyed in the 15th century by Bernese troops when they conquered Aargau. At a later date, the castle was rebuilt by the Hallwyl family and subsequently left to fall into ruin.
The ruins are located near the Säli-Schlössli restaurant and are about 1 hour and 30 minutes away on foot from the Olten train station. Take bus number 503 (toward Meierhof) from the Olten train station to the Dreitannenstrasse stop; the hike from the bus stop takes about 1 hour.
(Content from https://oltentourismus.ch/de/entdecken_erleben/sehenswuerdigkeiten/schloesser-und-ruinen/ruine-alt-wartburg-olten)
