Modern humans and Neanderthals once coexisted in the same place simultaneously. It's not very improbably at all if they are somewhat closely related. At least dwarves, elves and humans seem like they'd have a rather recent common ancestor.
Actually, I've rather liked the comparison of dwarves to Neanderthals...
Neanderthals evolved and split off from the branch of humanity before humans as a species fully formed, and left Africa for Europe before humans emerged there, and when humans eventually caught up with neanderthals in Europe, they largely coexisted for tens of thousands of years before the genocide wiped all the neanderthals out.
Neanderthals also had some distinct differences from humans - they were shorter and hairier (like dwarves), and as such, were poor long-distance runners, but were also stronger and more compact (like dwarves), which made them better suited for colder environments in forests, where they could ambush prey from close range (where their lack of running ability wasn't such a liability). They attacked prey larger than themselves head-on, in spite of the dangerous nature of their prey, such as trying to kill a wooly mammoth by jumping on its back and stabbing it with a wooden spear repeatedly, hopefully before it throws the neanderthal off its back and gores him/her.
In short, they were suicidally aggressive creatures with an absurdly high incidence of injury and a short lifespan. (Like dwarves.)
A creature like a dwarf, which is different from a human in that they are adapted to living in caves predominantly makes some evolutionary sense, provided they have a common ancestor to explain the very many similarities their people have. (Of course, that's assuming evolution, and not creation, since apparently, the world literally springs from nothing with creatures coming into existence at a random age at year 0.)
There's an interesting nugget of speculation- the possibility of Planned Communities. Ye Olde cities that grow naturally over time end up looking quite a bit like what those pictures do, but what happens when Rome burns and Nero decides to rebuild it along more organized lines? Given the nature of dwarves (or the immortal races) it is entirely plausible that they would plan their settlements far in advance, regardless of whether they ever expect to be a major city.
(Purely a technical aside, here...)
Nero rebuilt the chunk of Rome that burned down to be an absurdly massive personal pleasure palace for himself on the taxpayer's dime. That's when the story that he fiddled while Rome burned got circulated by his political enemies: They wanted to paint him as the guy who enjoys and profits from the suffering of the Roman people.
When Nero died, they tore that palace down, and built the Colosseum in its place. This was because the next emperor (who managed to last a while, at least, Nero's death sparked "The year of Four Emperors") wanted to make a public statement that his reign would be unlike Nero's by dismantling the pleasure palace, and building a massive public amusement center where average Romans could enjoy public games - using public land and money for public use rather than his own personal pleasure.
What I'm most wondering about while looking at those cities is what happens with all that open space in the middle of those buildings... Are they used as neighborhood parks? Or is there no way to directly access them, and nobody uses those open areas?
I also notice that the size of the buildings are all generally similar. Some houses are two or three times the size of the smallest buildings, but if you start talking about Roman towns, there were always the really wealthy, upper-class citizens who had estates with larger amounts of land and a personal garden and the like.
I also notice the "corners" of some of the ring-shaped clusters of buildings have unusually large amounts of unused space - the builders aren't trying to make non-rectangular buildings to take up some extra space that they could get away with building into...
Ancient and Medieval cities, where there weren't real building codes, were often expanded by the people living in them, which meant that middle-class families over generations would try to split or build extended conjoined homes taking up all the space they could get, and filling in the gaps (creating the sort of long, continuous rows of houses you see in those maps - all the space in the alleyways are filled in over time). Having those corners that don't take up the space they can take up looks unnatural because of it.