I visited the Lower German Limes in Germany and the Netherlands. The “Roman Disneyland” Xanten is already covered in other reviews. The museum in Cologne was in September still under reconstruction. Therefore I will focus my review on the Netherlands.
In my quest to find original remains in the Netherland. While most of the dots on our map seem to scatter around Nijmegen, it seems that none of these remains are actually visible. Then I stumbled upon Utrecht. Most (if not all) remains in the Netherlands are underground and in Utrecht you have the chance to go there. "DOM under" provides a guided tour to, you guessed it, an excavation site under the cathedral, or rather the part of the main square, that used to be part of the cathedral before a storm struck it down.
Space down there is limited. So you need to pre-book for a timeslot. We started in the basement of a house. There are a few exhibition items and the briefing took place there. Most important: there are remains of the roman walls visible within the building structure. For the second part, we left the building and entered the excavation site via stairs in the middle of the square. The Roman remains are only part of what I saw underground. There are several layers with part of the earliest church and the destroyed cathedral as well. However, there are Roman remains, which makes the Limes in the Netherlands not completely invisible.
The tour is fun. You will get a special flashlight/audioguide and can explore the (small) site on your own. Further, there are several movies to tell you the story of Utrecht. The guide was also very helpful. They seem to do this voluntarily and most ticket money goes into further excavations.
Be aware that Utrecht is not a very car friendly town. Parking is very expensive and getting in and out the city center takes some time.
You can easily combine this visit with the Rietveld-Schröder house. There are also a few forts of the defense line nearby. I combined the visit with