I love this! My father created a panorama with walkable waypoints like this for the Golden Temple in Amritsar and a few other historic sites back in the Shockwave/Flash days (something like 2001). Turned out to be some of my early learnings in building with Flash.

I also actually took my own series of photos on a whim a few weeks ago with the intention of DIY stitching my own pano and used to love using Microsoft's "old" (08-10) Seadragon/Photosynth tech.

I'd be very curious to learn more about your JS implementation. :)