The temple complex of Banteay Chhmar was constructed by Cambodia’s most prolific builder, Jayavarman VII (r 1181–1219), on the site of a 9th-century temple and is one of the most impressive remote temple complexes beyond the Angkor area. The Global Heritage Fund is assisting with conservation efforts and it is now a top candidate for Unesco World Heritage Site status.
The border town of Aranya Prathet (aka Aran) is known to Thais mostly for smuggling and gambling. (The casinos are over the border in Poipet.) For travellers, it's the busiest border crossing for trips to Angkor Wat and few actually stop here longer than needed to get their passport stamped. Though really, as border towns go, it's not that bad.