If future plans for human space travel include recurring visits to a Mars Base for research and exploration, an efficient and fast transportation system will be crucial for rotating crews back and forth between Earth and Mars and to resupply needed equipment and fuels. An innovative interplanetary transportation architecture is described that uses highly autonomous, solar-powered, ion-propelled Astronaut Hotels, dubbed Astrotels; small Taxis for trips between Astrotels and planetary Spaceports; Shuttles that transport crews to and from orbital space stations and planetary surfaces; and ion-propelled low-thrust freighters that deliver cargo to Astrotels and Spaceports. Astrotels and Taxis enable transportation of replacement crews, on short, frequent trips between Earth and Mars. Astrotels orbit the Sun with periodic flybys of Earth and Mars, while Taxis fly between Astrotels and planetary Spaceports. Two crews work on Mars with alternating periods of duty, each spending about 4 years there with crew transfers occurring about every two years. Also discussed are the production of rocket fuels using materials mined from the surfaces of the Moon, Mars and the Martian satellites; the use of aerocapture to slow Taxis at the planets; and finally, the estimated total life-cycle cost of this interplanetary transportation architecture.