the best is when you have a barb camp right where you want to build a base, on the perfect tile. clear that in the ancient area and you may have over 10 culture generating from that tile if you go that route. its actually made a difference late game, and helped me squeak by a diplomatic win recently. if its a forest tile, a 1/1 for example, I just leave it empty and wait. don't make the mistake of planting an academy on top of a former camp