Anno 1800's campaign tasks you with a variety of objectives, some of which involve finding specific people or buildings on the map. When access to your island's iron supply is blocked off, you're enlisted to find an Anno 1800 Demolition Expert on Edvard's island.
Here's the explosives shop location where the Anno 1800 Demolition Expert can be found.
Demolition Expert Location
When you're tasked with finding the Anno 1800 Demolition Expert, you might be tempted to look for a small character model to click on. That's not exactly the case with this particular quest.
The task itself will take you to Edvard's island, more exactly near its section that produces timber. Reading the quest's description will not only reveal that you should be looking for a building –the explosives shop– but also that it's one with a red roof.
The red roof tip should make it easy enough to find the building with the Anno 1800 Demolition Expert but, just in case, it's also surrounded by small craters and has crates, presumably containing dynamite, surrounding it. Simply clicking the building will trigger a cutscene which sees the demolition expert joining you. Afterward, you can continue your progress through the campaign.