In the game, there had been siege war events that large numbers of people had taken part in, Shin included. The ramparts had been enchanted with monster-repellent, fortification, and magic-resistant enchantments, so Shin felt it would be difficult to attack.
Shin suspected that it wasn't a town inside, but he couldn't tell at all what was really inside. Well, since it was surrounded by these reinforced walls, it probably wouldn't be a deserted ruin.