Another for literary types. Of what poem is this an extract (to me it is reminiscent of Lovecraft, but it isn't). What is the poem about?

Hearts thump and picks and shovels poise; transfixed, we stare in awe,

For, glowering in uncharted realm, within that musty maw;

A ravaged, long-lost citadel - appalling to the sight;

Eroded stone and sun-baked clay mired in primordial night.

Its guardians stir, incensed thus rudely waked from timeless sleep;

And yawn and stretch, and heel-to-toe, start from the gloomy deep;

An eerie file of mythic beasts lured from their hoary den,

Like night-moths to the lamplight, by this sunlit world of men.