I'd like to add a link to an excavation website – where does it belong?

A place resource is the best spot from which to link to general resources elsewhere on the web (or in print) that serve a "more information" or "see also" function. 

In contrast, an external reference linked from a Pleiades location resource ought to be providing specific evidence for the coordinates themselves (i.e., it is the resource from which the coordinates were sourced). 

Of course an excavation website might serve both purposes (and perhaps therefore merit a link in both contexts), but generally they provide so much more information than just the location and extent of the remains that they ought to be linked from the Pleiades place resource. 

From name resource pages we ought to have two kinds of references: (1) citation of a primary source that provides that variant (sub "primary reference citations", and (2) citations of discussions relevant to interpretation of the name itself (sub "references"). See, for example, how this is handled for Stauropolis.

For a discussion of the way Pleiades models and structures information -- including definitions of place, location and name resources -- please see the Technical Introduction to Places.