LEGO 6990 Monorail

The LEGO 6990 Monorail Transport System (1987) is the crown jewel of the classic Space theme and one of the most ambitious LEGO sets ever produced. A fully motorized, battery-powered monorail that runs on an elevated track through a futuristic space station — this was LEGO at its most visionary. With 624 pieces, a station, a control tower, and a working train, it was also one of the most expensive sets of its era.

The 6990 is a legendary grail set among LEGO collectors. It represents a golden age when LEGO took big swings with motorized, system-integrated builds. The monorail motor and track system were never reused in this exact form, making it a unique piece of LEGO engineering history. Complete sets regularly sell for eye-watering prices, and demand shows no signs of slowing.

This is a set where completeness matters enormously. The motor unit is the critical piece — test that it runs smoothly on batteries. The elevated track pieces and support pillars are specific to this set and commonly missing or broken. The translucent neon-yellow cockpit canopies chip easily. Verify all minifigures are present (the classic Space astronauts). The battery box should be free of corrosion. Instructions and box are major value adds. Be very wary of incomplete sets sold as "complete" — use BrickLink's inventory list to cross-check every element.