During the late 1950's or early 1969's Walt Disney Presents did a series that presented the theory that there were canals on Mars. The idea was that the canals were built in order to make maximum use of water. Telescopes revealed that Mars had polar ice caps that grew in the winter and melted in the summer. The theory was that the ice melted into water that flowed into the canals.
Since then we have learned that the climate on Mars is much colder and much dryer than we suspected. The polar ice caps are composed of frozen carbon dioxide, not frozen water. There may have been life on Mars in the past, but it was far too simple to make canals.