It's on the Quissett Campus of Woods Hole Oceanographic Institution, which is one of two physical locations for WHOI. It's behind the Reinhart Coastal Research Center, which houses Sea Grant, the Moorings and Operations Group and a geology lab.
Here's the Google Map view of the nest.
If you click on street view, you'll get a good sense of the overgrowth that surrounds it during the spring and summer.
People have asked for an idea of what the platform, nest, etc., look like beyond what can be seen on the camera, so here's an older picture of what it looks like. The perch is very popular with the birds and many times though it looks like the nest is empty, there are one or more sitting on it at any given time. In fact, as of this writing, there are two on it.