Aesch forms together with Dornach, Reinach, Arlesheim and Münchenstein an almost continuous agglomeration along the bank of the Birs. In 1793, Aesch was briefly a part of the «Departement du Mont-Terrible» and its inhabitants were citizens of France. At the Vienna Congress in 1815, Aesch finally entered the Swiss Confederation. Aesch is best known for its castle ruins: Münchsberg (sparse remains of an extensive castle structure with several towers and a circular wall), Schalberg (a partly preserved, imposing round tower), Engenstein (sparse wall remains) and Frohburg (also called «Tschöpperli» – significant remains of a castle representative of belonging to wealthy city nobility). Various reasons including the great Basel earthquake of 1356 caused the castles to fall into disrepair and ruin.

Schloss Angenstein in the neighbouring municipality of Duggingen is considerably better preserved. The inhabited castle is built on a rock spur on the Gempen plateau overlooking a narrow gorge (Klus) of the Birs river. To the other side of the Birs is the Blauen.

The Aesch Museum of Local History contains amongst other exhibits the ethnographic collection of naturopathy pioneer Dr h.c. Alfred Vogel. The museum is in a 400-year-old farmhouse, the «Kesslerhaus», opposite the council offices at Aesch Castle. Further attractions at Aesch are a late Stone Age dolmen grave that contained 47 mortal remains and the Catholic church, built around 1820 with glass windows and frescos.

Aesch has several discovery paths; the Burgengratweg (castles), Naturweg (nature), Weinwanderweg (wine) and paths along the Birs river and Klusbach stream. Aesch is an ideal starting point (SBB railway station and tram terminus) for a short hike to the pilgrimage site of Mariastein (SO). After Einsiedeln, Mariastein is the second most important pilgrimage site in Switzerland.