Sanctuary Park, the big Alpharetta office campus surrounded by North Point Mall and Verizon Wireless Ampitheatre, has sold for $265 million, as more investors bet on rising rents and occupancy in suburban markets. Rubenstein Partners L.P. purchased the 152-acre complex, one of the largest office parks along the Georgia 400 corridor. It includes nine mid-rise buildings and undeveloped land zoned for as much as 750,000 square feet of additional buildings.