Construction in the Near Earth Asteroid Region
The regions 60 degrees ahead and behind Earth in its orbit around the Sun, are two of the five "Lagrangian Points" of the Earth-Sun system. Objects that get into this region may stay there indefinitely, all the forces on them balanced out. While these points are very far away from Earth (in fact they are further away from the Earth than the Sun is), the amount of energy required to send a rocket to this region and land on an asteroid is in fact less than that needed to land on the Moon and return.
It is believed that there are hundreds if not thousands of asteroids in these "Near-Earth" regions, which are called "NEO"s (Near-Earth Objects). Over a thousand have been observed so far. Their composition is believed to vary, but some are believed to contain water ice, while others are believed to contain carbon and iron. Others are surely made of material similar to the crust of Earth and its Moon - silicon dioxide and metal oxides. There are also the usual equivalents of the "El Dorado" legend - asteroids made of pure platinum, (and gold??) etc.
The "NEA" region is thus highly attractive as a resource-rich destination. Note that sunlight is just as bright there as it is in Space near Earth. If water can be extracted, sunlight can be used to split it into hydrogen and oxygen - rocket fuel! Carbon, hydrogen and sunlight - metals can be extracted from metal oxides and carbon steel can be made.
The intensity of sunlight in the NEA region is the same as that near Earth, outside the atmosphere and out of the shadow of Earth - 1367 watts per square meter on average.
Solar background radiation and g-jitter