Okay, thanks. I didn't know that about previous cities, especially the part in Liaodong. However, I think I might still be unclear. I was talking about Wanggom was like. This ties in to what I say earlier in the post; if it was near or was Pyongyang, wouldn't it have been discovered already? I point to Hyung-il Pai's "Culture Contact and Culture Change: The Korean Peninsula and Its Relations with the Han Dynasty Commandery of Lelang" which notes "Unfortunately, these historical narratives [the part about the fortress of Wanggom and treacherous ministers in the Shiji] have not been confirmed archaeologically, since no evidence of fortresses that date to this period and that could have withstood a year of siege by Han armies has yet been found in this region." I'm not sure what to make of this discrepancy between archaeology and history, and whether Wanggom was really this heavily-defended city or something more mundane. Again, I know about the possibility of evidence being destroyed, but then again, absence of evidence shouldn't be taken to mean destruction of evidence.
I see your point, although as FDW said, North Korea is unwilling to disclose any information regarding the structure of Wanggeomseong, and the Japanese were looking for evidence that Korea originated as a colony, so they would have ignored anything which suggested otherwise. The structures and weapons do suggest that a centralized state existed in the region, but as you said, the remains of the cities themselves have not been found yet.