To get to Aachen from Maastricht, I took a bus which ran regularly between the two city centers. There were no boarder crossings, or anything, because of the European Union. I found this rather disappointing, as it would have been nifty to get stamps for going from country to country. They did, however, make us swap buses at the boarder. I am not sure why, especially because we didn't have to swap buses on the back, but we all got dumped off just on the Dutch side of the boarder, on a roundabout, and were picked up a few minutes later by a bus from the German side. Fortunately, the buses took the same ticket card, no matter what side of the boarder you were on.
You could tell a real difference between the landscape in Germany and in the Netherlands (or at least in the Eastern Netherlands). There are trees, and rolling hills, and different kinds of fields.
What was especially impressive were the castles (or at least the castle-like buildings) which popped up through the trees all over the place. I looked through the Google Maps to try and find what those castles might be and, while I couldn't find all of them, I think that I have identified one of them.
I think that this castle is actually a Benedictine Monastery in the Netherlands (the main road parallels the border for some ways). The Abdij Sint Benedictusberg is just across the border into the Netherlands and reflects some of the differences between Maastricht (which is kind of Catholic) from all the rest of the Netherlands. If you go
here, you can look at the monastery's webpage, including pictures showing the distinctive conical towers, plus a little information about the monastery.
The bus ride was only about 45 minutes long but it was really shocking to step onto the bus more or less understanding what was going on around me and then to step off it, less than an hour later, and not to be able to understand what anybody was saying or even really to read signs all that well.