518 Intervention
Buffy goes on her vision quest at the same location used for Restless (check out the page for it for more info on the location). I found the shot where Buffy first sees the mountain lion and where she walks behind it through some rocks. Apart from that, the photos are just of the location.

The outside of Glory's apartment was played by the
Castle Green Apartments at 99 S Raymond Ave, Pasadena, CA 91105-2046. There is a scene in this episode which consists of a long-shot of the apartment. The camera then pans down to Buffy and the Scoobies on some big rocks by a creek. While there is a park to the south of the apartment, it is completely flat with no creek and no rocks. There was a bit of digital to combine the two shots - where the scene by the creek was shot I have no idea.

5 Photos of Glory's Apartment (taken July 2, 2008), and 15 Photos of the vision quest location (taken January 14, 2009)

Glory Apartment:
Location
: 99 S Raymond Ave, Pasadena, CA 91105-2046.
How to get there: Take the 110, until it turns into CA 110 and heads into Pasadena. Turn left onto Del Mar, then take the first right onto Raymond. The apartments are on the left.
Mapquest here.
Google Earth Co-ordinates: 34 08' 37.18" N, 118 08' 57.97 W

Vision Quest Location:
Location: Next to Antelope Valley Indian State Park, around 16 miles northeast of Palmdale, CA.
How to get there: From the Spiral location, head north on 145th St. At the T intersection in 2 miles, turn right (east) on Avenue O. After half a mile, turn left (north) on 170th St. After a little over 3 miles, you'll see a few buildings on the right hand side, behind which is the rocky hills the scenes were shot at. The entrance I used to get in is 200 yards south of the buildings. Hike up to the outcroppings ahead.
Mapquest here.
Google Earth Co-ordinates: 34 39' 44.00" N, 117 51' 25.35 W

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BtVS 422 Google