Does anyone know the word for...

[mhw]

I don't know that there actually is a word for this concept, but this seems like a sensible place to start asking.

"A place/room/container where (human) skulls (and no other types of bony structure) are kept/stored/enshrined/preserved."

Ossuary is too wide, as it doesn't restrict the type of bone. Ditto charnel house.

I postulated calvarium, but

Comments

[pseudomonas]

The OED has a couple of citations for "skull house", though not recent.

[5]b. In sense ‘in which skulls are reposited’, as skull-box, -house.
1628-9 Sarum Churchw. Acc. (Swayne, 1896) 312 Henge for the skulle howse dore. 1654-5 Ibid. 330 Locke for ye skull house dore. 1859 JEPHSON Brittany vi. 67 In the apertures between the uprights which supported the roof [of the charnel-house] were heaped up skull-boxes.

[mhw]

Thank you.

In the meantime I'd also jokingly proposed skullery to myself.

I think I shall have to keep digging.

[goliard]

The OED actually lists 'skullery' in much the sense you're after:

A collection of skulls; a place for skulls.

1818 Blackw. Mag. IV. 327 The effect of the water dropping from the jaw-bones and eyeholes... It is not to be thought that an Irishman could contemplate such a skullery with unmoved imagination. 1908 Westm. Gaz. 31 July 1/3 On his excavating expeditions an annexe, usually known as the ‘skullery’, is almost invariably brought into use.

[hitchhiker]

i was just going to say 'skullery' (:

[rubberduckgrrl]

I'm not sure the answer, but I just visited this criptoportico/crypt - and the site might hold an answer for you.