I have a book from 1979 or thereabouts with the ringworld illustration in it from this site. Does anyone know about that series of books, "world of tommorow" o

I have a book from 1979 or thereabouts with the ringworld illustration in it from this site. Does anyone know about that series of books, "world of tommorow" or something like that that talked about terraforming Mars, future transportation and health, etc? I really loved that series as a kid but can't remember the name.