This isn't an antique, but there is interest here in round vault doors. Most of which are antiques.

Gunnebo Security Group has a round door they call the Centurion-RD, see https://www.gunnebosafestorage.com/e...s/Centurion-RD for example. It looks like antique doors in general principles. It does have a flat bottom like the modern product from Vault Storage Incorporated (VSI). It uses roughly the same boltwork as Benjamin Tripps's from 1906, with the traditional 24 locking bolts. And sadly (to me) it seems to include a fair amount of electronics (keypad outside, and the image shows a wiring harness on the inside).

Click image for larger version. 

Name:	Gunnebo Centurion-RD.jpg 
Views:	32 
Size:	570.4 KB 
ID:	22401 Click image for larger version. 

Name:	Gunnebo Centurion-RD outside.jpg 
Views:	31 
Size:	236.0 KB 
ID:	22402

In 2011 they announced a contract for a door in Qatar for a private gold reserve (https://web.archive.org/web/20150504...rproduced.aspx), this might be the same product.