Episode 7 ("The Hub") involves agents Ward and Fitz going into rebel territory in South Ossetia
(on the Georgian-Russian border) to destroy a weapon known as "The Overkill Device".

Many of the early outdoor scenes were shot in L.A.'s Griffith Park,
with a lot of CGI to add snow-capped mountains to the horizon.

But the big finale, at the rebel headquarters (where you see a lot of power transformers) was filmed at
the old Edison Power Plant, (now called AES) at 1100 N. Harbor Drive, in Redondo Beach, CA.

That's across the street from the Redondo Beach Marina, and a few blocks north
of the Redondo Beach Pier (where they filmed a lot of "The O.C.")

(Ignore the snowy background glimpsed in some scenes here - just CGI again.)

Here is a Google StreetView of the location.