Christiaan Huygens did not make any markings on Mars. He was the first person to observe the planet through a telescope in 1659, and he discovered its largest moon, Titan. He also drew a map of Mars, which showed a dark feature that he called "Syrtis Major."

While Huygens observed and documented features on Mars, it was not until later observations with improved telescopes and techniques that the markings we now know as canals were seen and interpreted.