"We are moving next to a nice city."
Translation:Egy szép város mellett haladunk.
There was a similar question recently where I suggested "moving along" as a good possibility for halad, especially when it means literal motion. I think that works well here: "We are moving along next to a nice city." A motion verb together with "past" might also do a good job: "We are driving past a nice city" (this suggests the city to your side - you can see it through your car window as you move along). If "driving" isn't appropriate, then "riding" or "running" or whatever would do just as well.
"Proceeding past" or "proceeding by" the city are possibilities that get the meaning right, but they sound a little formal. "Proceed" and "proceeding" have an air of school or law or other formal settings, at least to me.