Often, when a player is new to Evony, he/she gets confused on how some buildings can be under 5 minutes, yet he/she cannot instantly construct that building. The reason for this is that the 5 minute instant build is based off of the “base time” it takes to construct a building. Sometimes, you may be able to construct a building in under 5 minutes, or even under 4 minutes. This is because you have a castellan with at least decent politics. If you have a castellan in your city that has any politics stat, the build times are faster (the higher, the faster). In addition, if you have any construction technology, the build times are faster. That 5 minute speed up only works with buildings whose “original time” is under 5 minutes, not your upgraded time.