The Richmond Hill David Dunlap Observatory (RHDDO) houses the largest telescope in Canada. A number of important studies have taken place here, including providing the first direct evidence that Cygnus X-1 was a black hole, pioneering measurements of the distance to globular clusters and the discovery that Polaris was stabilizing.

In 2019 it was recognized as a National Historic Site.

The bare field below is being rehabilitated with native vegetation as part of the conservation management plan.