Saalburg Roman Fort (ORL11) is an absolute treat. Near Bad Homburg and part of the Upper German limes, it has been a Unesco World Heritage site since 2005. Home, most famously, to the Cohors II Raetorum civium Romanorum equitata it was abandoned in the AD260s. What makes the site so special is that the fort was reconstructed at the end of the nineteenth century, enthusiastically encouraged by Kaiser Wilhelm II. It is the most reconstructed fort on the limes and as such there is a real sense of place in the camp which makes visits to less well-preserved sites much easier to understand. For those with German, the German Wikipedia page is a great read.
Gateway to the Saalburg - statue of Emperor Antonine
Inside the assembly hall
The courtyard of the principia