Having read Zeitspringer’s recent post (in German) about the earthworks in Holzhausen near Fürstenfeldbruck, I felt inspired to tell him (and you) about a patch of farm country that has become one of our regular walking routes. It’s got beautiful scenery, crosses through fields and woods, often has lots of horses (from the stables at Achselschwang) and – to my enduring delight – features two ancient landmarks: a section of the Roman road to Augsburg and a pre-Roman earthwork, known as a Keltenschanze or Viereckschanze (the red line and the red square in the image shown below, in a screenshot from the always interesting Bayerische Denkmal-Atlas).
I won’t suggest a specific circuit because the route we usually take starts at the parking area off of Landsberger Strasse, and may not be the best for visitors coming on foot or by bicycle. Those unfamiliar with the area using a combination of public transportation and their own two wheels might consider alighting at Geltendorf and riding through St. Ottilien, continuing south to Utting. One can also catch the Ammerseebahn at Geltendorf and take that train directly to Utting (but be aware that it’s a long uphill climb to the main road. Alighting in Schondorf and taking the cycle path along the main road will be easier on the legs, and probably no longer.) If you really want an adventure you could take the S8 regional rail line from Munich to Herrsching, cross the lake by padde steamer to Holzhausen or Utting, and then pedal from there.
There is a sign with information about the Roman road posted just south of Achselschwang, and one in front of the Keltenschanze.
Afterwards, pedal down to the water’s edge in Utting, where you’ll find a nice restaurant (visitors) near the boot landing as well as a lakeside beer garden (locals). From there it’s only about 100 meters uphill to the Utting rail station (or a boat ride back to Herrsching).
The PDF found here (in German) contains a good introductory description of the Roman road as it passes west of Utting.
Older posts on the Via Raetia and the Keltenschanze:
The Practice Room 
Another option to get to the Keltenschanze is to take the train to Schondorf, and hike along the Ammersee Höhenweg (just follow the signposts from the station). It’s a nice walk with great views of the lake and the alps.
I didn’t know there were signposts at the station — excellent idea!