The rotunda at the former Cleveland Trust building has several nice Hollar vaults; the building is currently being renovated. A photo essay at http://www.artographyonline.com/blog.../rotunda-vault includes imagery of an emergency door that's unusual in that it is a small chamber with two separate doors:

Click image for larger version.  Name: Cleveland Trust 17.jpg  Views: 44  Size: 374.5 KB  ID: 12066

We've seen double-door or "vestibule" main doors but this is the first such emergency door I've run across.