The available information on the burial crypt of the Schwarzenbergs proved to be rather fragmentary. To the best of my knowledge, it was located near the altar of St Nicholas of Tolentino in the Augustinian Church and was in use from 1682 to 1789. By the spring of 1757, the crypt had become the final resting place of three reigning princes, two princesses consort, another married princess née Schwarzenberg, and four children.
Admittedly, I have never seen the crypt with my own eyes. I find it difficult to imagine that it would be accessible to outsiders at all, and I have not attempted to apply to either the church authorities or the family for a visit. Thus, I cannot confirm whether the principal landmark — the altar — still exists, nor what its precise location within the church might be. Even the terminology is somewhat unclear: both “crypt” and “chapel” appear in the sources.
The description of it is therefore purely imaginative. Although rooted in research of academic quality, my ambitions for the narrative are primarily artistic. It seemed disproportionate to trouble those responsible merely in pursuit of such a high level of historical accuracy.