CityBuiding is Simple! The relation of the City HeightenedMultiplierPeriod(HMP) on NewBuildings and NewMonuments to TreasureBox(TB) is more difficult.
I Build assuming the HMP on the Buildings is 4Days and Monuments is 2Days. During this time, your TB gets more Power towards you Prize! After that time they “normalize” and the HMP ends. Thats when I MonumentMake and Evolve and Replace my buildings.
All the Buildings and Monuments have TierLevels listed in the Building Shop.
T1-6 Can MonumentMake 100Gems worth of Bldgs a Level1(L1)(T7) Monument. All L1 and T7s are worth 100Gems.
T7-9 Can Evolve a L1 into L2. It takes 900Gems worth of Bldgs and Monuments to Evolve your L1Mon to a L2Mon worth 1000Gems.
T10-14 Can Evlove a L2 into L3. It takes 9000Gems worth of Bldgs and Monuments to Evolve your L2Mon to a L3Mon worth 10000Gems.
T14-18 Can Evlove a L3 into L4. It takes 70000Gems worth of Bldgs and Monuments to Evolve your L3Mon to a L4Mon worth 80000Gems.
You Can actually build your City 100Gems at a time!
(2)T6 Buildings MonMake to L1(T7) Monument worth 100Gems.
MonMake (9) more and EVOLVE that L1 to a L2(T10) worth 1000Gems.
Do that (9) more times and EVOLVE that L2 to a L3(T15) worth 10000Gems.
Do that (7) more times and EVOLVE that L3 to a L4(T21) worth 80000Gems.
Daunting Right, LOL 
If you use the HMP while Building, Your TB will reward you! Soon you will be adding T7(100Gem) Buildings to your process, Then T8(200Gem) Buildings, Then T9(500Gem) Buildings! Thats as far as I go with my City Building I use (1)L1+(1)T9+(2)T8s to EVOLVE a L2 and use (10) L2s to Evolve My L3s, Over and Over, LOL! I keep my L3s and Collect Daily at 24Hrs Because I like my Wine/Gold Cards! Remember your TB (MEAT) gives you 95% of your Rewards here. Use the HMP while Building your CITY (GRAVY).
GL Yall, Hope this Helps someone