First post here so, first of all, let me thank you guys for what have been learning over the years by just reading these forums. I haven't had the time to read all and watch the videos about Civ VI, so really sorry if this has already been addressed. We all know that district cost scales with techs (and civics) through the formula on the xml file, but what I didn't know is that once you lock a tile to a district it also locks your hammer cost. So you can start a campus on a city at turn 50 locking the cost at around 100 hammers and finish it at turn 100 when districts are going for 200+ hammers. The downsides are that the tile can't be used for anything else, it limits the ability to construct other districts and you might need to gold buy the tile to place it.