Area at the border between Macedonia and Kosovo, to reach from macedonian side it's a long gravel climb, up to the border, loads of motorbikes going up but still very pleasant climb! From the border on the road gets paved. Careful, some tell it's illegal to cross there
Border crossing is only permitted for locals (people who live near the border). The road on the Kosovo/Serbia side is in very good condition and very pleasant. On the Macedonian side, it's rocky but perfectly manageable with gravel.
Despite the illegality, it is possible to cross, even when border police are present. It's a bit of a lottery.
Please take this into consideration before venturing there.