The last remaining gate of Delft, Oostpoort (Eastern Gate) was built in the 1400s. The other seven gates have long since disappeared. The official Delft website has a nice drawing of what the city looked like when it was surrounded by walls.
Note especially the dog at the feet of the watchman. This is what you would see if you entered Delft from this city gate — two very imposing figures watching your every move, judging you.
Here is the gate from the inside looking out. This shot is actually close to the lake where I took the picture of the ducks. Interestingly, the structure also seems to partly be a private residence — and there is also an art gallery inside. The two shots don’t do justice to how big it is – more like a castle.