The Eden Project
The Eden Project is a large-scale biospherics project based in Cornwall, South-West UK. Comprising of a system of huge "biomes" (bio-domes), they sustain plants in their natural environments. Replicating the climates of the Mediterranean, Tropics and other warm locations, a variety of plant species flourish. Domes of a similar design could be used on an established Mars colony to create large greenhouses to grow food and provide a source of comfort to colonists.