was the perspective where that flag is? im working on perspective and at the moment its really being difficult and even illusive in my own opinion and i was just wondering.. the piece is amazing to say the least though i love it and even might have use some of the styling and designs in one of my own pieces, although im not entirely sure. i saw your picture and started drawing, im not sure it the two event coinside in anyway. but anyways, great artwork im envious!
Makes perfect sense, actually. The last world I created for a GURPS game (tabletop RPG) used a similar concept: the Dwarves (being the most magically savvy) built their enchantment laboratories on mana wells, because the enchantment didn't take as long (and when enchanting an item takes several months per enchantment, saving a few weeks makes a big difference, especially since they got hourly rates and had to quote the job up front). But they couldn't build them too close, otherwise the magic energies had a tendency to overly hard to control, and would cause some rather extreme issues with the enchantments.
Well, when building worlds for RPGs, you really do need to put a lot of thought into it. Otherwise, the other players will either pick it apart, or abuse any loopholes they can find. So you have to build as much as you can with as much thought as possible, and assume that the people who inhabit your world will be as efficient with their tools as the average player will be. Any "loophole" in the system will have already been exploited by the npcs who work within that system.
So, to use your city image as an example: The mana well is not necessarily liquid, or unstable. The rock that the city is built on is actually quite stable, and sitting in the middle of the pool; you just can't see it due to all of the special effects of the glowing well. Or, the local mages who helped build the city worked the structural integrity into the well itself with their enchantments, so as long as the well exists, it not only supports the city, but strengthens it as well. (In this case, sort of like how General Products spaceship hulls are built with tiny power sources in them to artificially strengthen the atomic bonds.)
And how would the local mages take advantage of this? Even without knowing the details on how the magic works in that world, one way to take advantage would be to build things that couldn't exist without that active power source: floating gardens (as in, suspended in air); sculptures or structures that couldn't support their own weight; non-corporeal streetlights; etc. It's when you work out the details on how the magic works (ie, the local physics) that you can really figure out the most efficient way to utilize it.
Sorry for the rambling; I used to GM and worldbuild as a hobby. I once detailed out the daily routine for enchanter mages just in case anyone wanted to know what those dudes are doing for the 6 months it takes to enchant that +3 flaming sword.