Thanks--cool theme! The wordplay for 4a was clever. I also really liked 180 AD though i was stumped on it for a while! Could you please explain the wordplay for 2d and 5a?
What I was going for was:
2d: R at the end, then the rest is climbing (bottom to top) A G (grand) then OUC anagrammed (couch with the outside letters dropped)
5a: first letter of ate (A) + ARENA anagrammed (arena is sand in Spanish)