I am just curious if there is a maximum amount of buildings you should have in your city, (before turning some into monuments)
I am asking people who are VIP’s for life to list how many buildings they have in their city.
This varies by each person and what they are trying to accomplish. You do want to try to invest in your city each day if that is possible. It is recommended to buy Tier 6 at a cost of 50 Gems (or 1,250,000 building bucks). Then you can use 2 Tier 6 to evolve to a L1 monument.
There are variations of thoughts on how to evolve to the L2, L3, L4 monuments, which all take some time. But if you are regularly buying Tier 6 and evolving those to L1, you can use 10 L1 to evolve to the L2.
Cruisinpast has a suggested method to buildings and evolving in his profile which is worth reading.
Night Guy has a topic here in the Help section. Tips and Tricks for beginners and Veterans, I think it is called. He also gives a tremendous amount of suggestions on this and other topics.
I think the goal in order to max out how much the treasure boxes pay out in your city is $1,800,000,000 gems in buildings. That is a lot and just takes time. That is why being consistent in your progress is more important than how fast unless you are buying Gems with your money all the time and are able to buy buildings faster.