Thanks for understanding. This is first day I've felt reasonable normal again for a while. Hope you escape it, it's a killer.
This ornamental hammer you've found is certainly a rarity. The other one I appraised a while back was similar but not identical. It was an ornamental hammer that dated to around 1907 designed and patented by a Charles T. Hennig, with a patent number: D35100.
Yours is even more elaborate, and with the bas relief figural details, cherubs, and a man's head in a hat and costume of 17th century Europe, and of course the curious compartment. This is almost certainly a one-of-a-kind commission. My guess is that it's European, most likely Dutch, German or possibly French and late 19th century in date considering its nod to the Historisme of design that was fashionable at the time.
It was customary in those days to present ceremonial tools, elaborately embellished with decoration, as presentation gifts, typically inscribed with the names of the dignitaries and engineers to be honoured, for major civil engineering projects such as the completion of a large building, railroad, ship and especially bridges. This looks like part of a hammer and trowel set to celebrate the opening of a new bridge. The 19th century French were particularly fond of presentation trowel and hammer sets for bridge builders.
The compartment is a curiosity. Perhaps to hold a souvenir item or two from the construction -and thus create a miniature time capsule of the event, perhaps.
As for value, a one-of-a-kind item like this with no comparables and no provenance is really hard to put a firm price on.
The Hennig patent hammers sell at auction in the range of $150 - $300, so it's got to be worth more than that, but it would not be considered as valuable, say, as a sterling silver presentation trowel, or Freemasonry/fraternal order, etc. object.
So I would put it in the $300 - $500 range. Full retail/replacement/insurance value: $1000.
Hope this helps!