Over most of the last millenium, the village of Zwiefalten, in the Schwäbische Alb, has been the location of a Benedictine monastery. The cathedral that is part of the monastery complex is one of the most elaborate and beautiful example of Baroque design in the region (see also the Birnau church on the Lake Constance Loop tour).
While the church is still in use, the rest of the monastery complex is now a large psychiatric treatment facility. A stroll around the church, which will take you across small brooks and through nice gardens, makes for a pleasant walk. Across the street, a brewery has been in operation for the last 450 years - mostly run by the monks, but now in private hands. The brewery restaurant is a nice spot to catch beer and a bite of lunch.
From Zwiefalten, our route takes us along the Danbue River. If you enjoyed the Zwiefalten church, and have a little extra time, there is another Baroque church just up the road in Obermarchtal. Continue on the road from here to the village of Blaubeuren. The highlight here is the Blautopf (Blue Pot). Here, a good size stream literally flows up out of a large hole in the ground. If it has not rained recently, the water in the basin is a lovely medium blue.
Another attraction in town is yet another monastery. While neither the church or the monastery is particularly noteworthy, the wooden high alter in the old section of the church is well worth the price of admission. The alter has a couple layers of doors that open out to reveal several different scenes. Make sure to check out the model of the alter in one of the outer church rooms to see how it all works.
The trip to Zwiefalten and Blaubeuren, including a stop for lunch, takes about 7 hours.
A trip to Zwiefalten or Blaubeuren could be combined with a trip to Ulm. You could do all three, but it would be a very long day. Blaubeuren is on highway B28. If you are going to Blaubeuren and then Ulm, follow the Ulm scenic route itinerary and stop off in Blaubeuren. If you are going to Zwiefalten, follow this itinerary until it reaches the B28 around Blaubeuren, and then follow the B28 into Ulm.
Another worthy sight along the way is the Lichtenstein Castle (Schloss Lichtenstein), south of Reutlingen. This is another fairy-tale castle, with towers and turrets, perched on a rock cliff. This castle is quite a bit smaller than some of the other castles in the area - small enough that you could actually imagine feasibly living there. The castle can be visited on a 30 minute guided tour (German only), and then you can walk around the castle grounds. Again, it is probably too much to try to do the castle along with Zwiefalten and Blaubeuren, so you'll have to either get an early start, or skip one of them.
Head north out of Bondorf but do not get on the autobahn. Instead follow the B28 through Tübingen to Reutlingen.
Exit the B28 in Reutlingen onto the B312, then follow the B312 through the city.
You will see the Lichtenstein Castle as you start heading up the hills south of Reutlingen. Continue along the road as it climbs steeply out of Honau. If you choose to do this part of the itinerary, look for and follow the signs to Schloss (or Burg) Lichtenstein once you are on top. There will be a marked parking lot off the road to your left. Walk, following the signs, to the castle. When you are done, go back the way you came, turn right on the B312 and continue on to Zwiefalten.
It is impossible to miss the church in Zwiefalten. There are several parking areas around the church. The brewery is across the main street that brings you into town.
Leave town on the same street, following the same direction, as when you arrived.
Follow the signs to Ehingen. This route will take you across the Danbue River, where it then joins the B311
Obermarchtal is to your left off of the B311 between Zweifalten and Ehingen. If you choose to do this part of the itineray, exit the B311, visit the church and rejoin the B311 in the direction to Ehingen.
In Ehingen, turn onto the B492 in the direction to Blaubeuren and/or Ulm.
Once in Blaubeuren, follow the signs to the town center and park in any of the parking lots there. There are sign posts at almost every corner that direct you to the Blautopf. The kloster is next to the Blautopf.
When you leave town, follow the signs to the autobahn. Once you reach the autobahn (the A8), head in the direction to Stuttgart.
In Stuttgart, take the A81 in the direction to Singen. Exit the A81 at the Herrenberg exit.