[geoschmo]

Advantage to building a sphere/ringworld.

• Lot's of room for facilities
• 150% on all three resource values
• Room for lot's of people, so your production and construction facilities can get tremendous bonuses
• Lot's of cargo room for weapons platforms and fighters.
• Protects your star from star destroying weapons and events
• Cannot be blown up by planet destroying weapons(At leat in the stock game)
• Really, really cool to say you have built one

Disadvantages

• Takes a lot of reasearch to get the tech needed
• Takes a lot of resources and time to build the neccesary ships/bases to construct one
• Usually by the time you get one, you don't need one anymore