penetralia

noun

1. (plural, plural-only)The innermost, secret or hidden parts; mysteries.
2. (plural, plural-only)The innermost parts of a building, such as a shrine, recess or a sanctuary within a temple.

   “I believe, had I been in the inmost recesses of my habitation—the very penetralia—your eagerness would have surmounted bolts, bars, decency, and everything.”

   “He wished to be what he called "safe" with all those whom he had admitted to the penetralia of his house and heart.”

   “[…] Bob's countenance was sublimed by his recent interview, like that of a priest just come from the penetralia of the temple.”