Having never been there, I was pretty interested in using the site to discover the Chapel... until 4-5 minutes in and the Flash still wasn't fully pre-loaded on my 50 Mbit connection!

While the final size of the download might remain the same in the end, only loading the requested zoom level à la Google Maps instead would give it a way more acceptable "instant-like" feeling. Pre-loading the entire thing before users can interact is just plain bad usability.

If it wasn't a famous landmark, I would have left the site within 30 seconds. Still, I applaud the initiative and am happy to have seen the place in such details!