Here in Australia, they ran/run at around 580VDC, because that's what you get when you mercury rectify 415 VAC three phase (240 V phase to neutral, we skupped the whole 110/115/117/120 V nonsense). The only reason it was DC was that traction electric motors were DC at the time. And of course two wires (one near-ground potential rail and one overhead cable) is much easier for transportation than three live wires.
But AC won because it could cover a much larger area, so was far cheaper in terms of wire,
Yes, because of low frequency transformers.
The other huge advantage of AC is that you can turn it off with a cheap switch. The arc is self quenching because the current crosses zero every 8.3 or 10 milliseconds. Also fuses are cheaper for the same reason. That's a major nuisance for DC over about 24 V.
Edit: yet one more advantage of AC, at least outside of North America where three phase seems to be uncommon, is that induction motors run nicely at utility frequency, at a convenient 1800 or 1500 RPM, less a little. They happily run continuously for years, and don't have brushes that wear out.