Awarded for placing colony buildings. If you remove a building from one of your colonies, it takes it away from the count of how many buildings you have - for example, it is possible to go from having placed 100 buildings to zero if you remove buildings from your colonies, in which case you have to start working towards the highest level from the beginning - but you will not lose your current level of the badge. The count can go negative, though the UI shows the count as zero in that case. Colony city halls are counted towards as buildings, so it is possible to achieve this badge at level 5 with only T0 colonies by placing lots and lots of colonies. However, this is very expensive and unreasonable.