I have looked at the forum for someone that has been on the road 40 and then 231 in Serbia, from Trn (in Bulgaria) and then over the border checkpoint at Strezimirovtsi into Serbia. From there the road 40 goes SSW to the big lake Vlasinsko jezero, and then the road 231 turns SSE towards Bosilegrad. It was rated a 5 star in a post from 2016 on this forum. Does anyone have a fresher update. I am particularly interested in the road surface. Is it smooth asphalt or is it gravel in parts? Planning a road trip for this summer, and I believe the 231 could be a "magical" road, but wouldn't want to do 70+ kilometers on gravel.