The Ringworld Engineers (Orbit Books)

also by Larry Niven in our collection:

• Lucifer's Hammer
• Inferno
• Man-Kzin Wars
• A Gift from Earth
• A Hole in Space
• The Long Arm of Gil Hamilton
• The Moat Around Murcheson's Eye
• The Mote in God's Eye
• Neutron Star
• The Patchwork Girl
• Protector
• Ringworld
• Ringworld Throne
• Tales of Known Space
• The World of Ptavvs (Tales of Known Space)