Macmillan Readers Intermediate Level: Rendezvous With Rama

Rendezvous with Rama is an adapted Intermediate level reader written by Arthur C. Clarke. In the year 2131, a fast-moving object is detected entering the solar system. The object was identified as an asteroid and was named Rama. Scientists boarded a space flight to view Rama and soon discover it is a huge hollow cylinder. Who built Rama and why?