What is "vaultings"

Usage examples of "vaultings".

From the rear of one great temple stretched a low black passage which Carter followed far into the rock with a torch till he came to a lightless domed hall of vast proportions, whose vaultings were covered with demoniac carvings and in whose centre yawned a foul and bottomless well like that in the hideous monastery of Leng where broods alone the High-Priest Not To Be Described.

Gothic arches but Russko spires, except that in low gravity those vaultings soar while those domes bulge … and yet it isn't mismatched, it's strong and graceful in its own way, it belongs on Aeneas as … I do not.