Missing buildings when traveling after downloading get to work

Are you playing with any custom content? If you do, disable it by moving your Mods folder to the desktop (for example) and try to play. If it gets fixed, then there's an outdated Mod in conflict with the game.

Try also to make a new game instead of loading it and check if the buildings are gone too, maybe it's your savegame which has that bug. But I'd bet it's due to Mods and Custom content.