You must be careful when exploring the areas around Fort Worden's old fortifications. When these were built in the 1890s, the fall protection for military personell were minimal, and few upgrades happened over the years until their closure in the 1950s.
Note, for example, the main photograph here. Walking up the hillside that runs away from the beach it would be very easy to abruptly run out of hillside and fall into the pit that used to house one of the huge gun carriages.
Such open areas are very common throughout the old fortifications, so it would be best to keep control of children as well as make sure that you don't run anywhere unless you can clearly see what is ahead of you.
There are a few hand railings here and there, but beware that they may not be that stable after years of exposure in the salt water, and also notice (in the several locations where they actually exist) that the early 1900s did not really protect against small children ducking under the railing!
And never get too close to the edge of anything!!!
You will notice that there are certain parking places in Port Townsend that never get used, and others that only get used by cars from out of state.
This is because, if you look at the ground, you will notice that those parking places are near utility poles or roof ledges that are popular with seagulls.
The result is, well, a fairly nasty mess if you don't pay attention and park under one of these locations.
Even worse are a few outdoor cafe tables that are in some of these hazard spots. There are some good reasons to have umbrellas over your table in Port Townsend, even when it isn't raining.