Listed Buildings Map
This is an experimental map using Google Fusion Tables as the data source. As a project under development it's very much subject to change (not only because I'm still working on it, but because Fusion Tables is itself still a Google Labs feature and hence undergoing continuous development). However, it does seem to work reasonably well, so I've released it to the world as a first draft!
Key
 Grade I |
 Grade II* |
 Grade II |
 Unknown |
The map only shows the first 100,000 items in the visible window, so the overview can be a bit misleading. Once you start zooming in to lower levels then more buildings will show up.
For an overview of all the properties in the database, then try the heatmap visualisation.