Large museum with a great collection of ancient art from the Roman Rhineland: Bonn itself of course, but also Cologne, Xanten, and so on. Among the Roman objects is the famous cenotaph of Marcus Caelius. Even more famous (but not Roman) is the skeleton of the first Neanderthaler, which was discovered in a nearby valley.
There are 44 items in Bonn, Rheinisches Landesmuseum:
Xanten-Birten, Dedication to the Capitoline Triad by a standard bearer of XXX Ulpia Traiana
Xanten CUT, Treasure
Reconstruction of a Germanic warrior
Niederzier, Portrait of Gordian III
Bonn, Relief of people sacrificing to the Aufanian Mothers