1 Universities. Before the university, families hired teachers to teach their children and if the children didn’t like the teacher they would fire them. The university kept the children from firing the teachers.
2 Wine Press. The wine press stopped people from suffocating when trampling the grapes. It also made a cleaner and better wine.
3 Ribbed Vault. The ribbed vault made ceilings stay up without the need for pillars.
4 Chimney. The chimney let out gases from fireplaces or stoves without having a hole in the roof.
Stuff That Jack Built 