Megastructures

Megastructures are the most iconic late-game building type in Stellaris. Most require unlocking a specific tech first, and some also need a prerequisite “megastructure shipyard” or similar facility already built.

What to check before you start building

• Megastructures are expensive and slow, tying up a large share of your alloy and influence output while under construction — it’s best to start them when your empire’s finances are stable and there’s no war looming.
• Prioritize megastructures that directly support your current development direction — a tall/science build should prioritize energy or research megastructures; a wide-expansion build might prioritize logistics or military ones instead.

A common new-player mistake

A lot of new players start building the moment a megastructure tech unlocks, without checking whether their long-term resource output can actually support the investment, which stalls other projects. Run the numbers on your long-term production gap on the resource panel first, then decide when to break ground.