Smithsonian Resident Association Program lectures
There actually seems to be an even wider series of lectures on the Celts, by various professors, called "Celtic Connection."
Another interesting series is Signs and Symbols in Western Art, which includes lectures on June 28, July 5, 12, 19, 26 by Dr. Angel Puglisi at Georgetown University. The relevant lectures are June 28 (The Graeco-Roman World) and July 5 (The Christianizing of Attributes).
There's also a lecture on June 30 by Kathy Reichs on her new book Cross Bones, which apparently "raises questions about the Holy Family and their possible burial in a secret crypt." I've not read it, but that sounds interesting too.
Another series is on the Glorious Islands of the Mediterranean, with lectures on July 5 (Spain's Balearic Islands), 12 (Malta's Temples of Stone Age Genius), 19 (The Isle of the Cyclops: Sicily, Pantelleria, and Lampedusa), 26 (Ancient Sardinia). Most of the lectures are with Michael Hornum, except for July 12 with Linda Eneix.
Then there's a whole day, July 9, on The Gnostic Gospels with Dr. Bart D. Ehrman of University of North Carolina.
Next is a half-week on The Pharaohs of Ancient Egypt, July 11-14 (once a day), with Dr. Bob Brier of Long Island University.
There's another one-lecture program called A Language History of the World with Nicholas Ostler, who is apparently one of those people who makes everyone else feel inadequate, because he has a "working knowledge of 18 languages." Right. I'm trying to conquer three for right now. Anyway, that's on July 13. And he quotes Themistocles via Plutarch on that page.
We also have The Art of Tuscany with Dr. Christiane Joost-Gaugier. Lectures are July 13, 20, 27, August 3, 10. As always, the first is the most relevant, covering "Ancient and Medieval Tuscany." However, they are all relevant to those with an interest in the Classical tradition.
The last directly-relevant lecture for July is on July 19 with Dr. Steven Rutledge of University of Maryland, called Fiddling with Nero, appropriately on the anniversary of the fire in Rome.
I would, of course, advise that you look through the listings yourself, as there are several other interesting lectures, some of which are at least tangentially related. However, there is only so much I'm willing to type up! They also already have listings for August and September, but I shall go through those closer to their dates.
Unfortunately, they all cost money, which is why you won't be seeing me at most of them. The cheapest and most affordable to students would be the one-lecture programs, which include "Fiddling with Nero," "A Language History of the World," and Kathy Reich's lecture.