Saturn is a large, bright planet, and according to NASA, it has been known to humankind since ancient times. The first person to view Saturn through a telescope, Galileo Galilei, was also the first person to ever see the planet's famous rings.
Given proper conditions, Saturn can be seen with the naked eye from Earth. It appears as a bright star, and prehistoric peoples could see it in the night sky. It wasn't until Galileo, the famous early pioneer of astronomy, used his primitive telescope to look into the heavens that humankind understood that Saturn had rings.
Of course, Galileo's telescope was so basic that he actually couldn't tell what Saturn's rings were at first, and he thought they were moons. After years of looking and considering, in 1616, Galileo guessed that the two objects he was looking at were a set of "arms." He was on the right track, but not quite there with understanding the planet's ring system.
In 1659, Christiaan Huygens, another pioneer of astronomy, took advantage of better telescope technology than had been available to Galileo to continue research into the planets. He was able to see Saturn's rings, and he also discovered Titan, one of Saturn's moons.