There’s no particular reason to put online this drawing by Graham Sumner, except for the best reason of all: that I like it. What you see is the Roman naval base at Velsen, just west of Amsterdam, which was in use during the reign of the emperor Tiberius. It is almost certainly identical to the fort named Flevum mentioned by Tacitus. You can read more about it here, or in Edge of Empire.
You can order Edge of Empire here.