When a project becomes so big that people start calling it a mega project it’s safe to assume that the budget is going to run pretty high. Construction is infamous for being an industry where budgets are a lot more like fanciful suggestions than hard guidelines. Because of this many projects end up costing far more than expected.

From an airport built on an artificial island that looks like it’s floating in the ocean to a theme park in dubai that will cover over 100 square miles once completed here are five of the most expensive mega projects in all history.