The Pylons are small truncated square pyramid-like buildings that litter the landscape of the Land of the Lost. Pylons are often golden, tall and narrow, spaced approximately every quarter mile in a regular pattern. The surface of a Pylon is polished to a mirror-like precision and extremely smooth to the touch.
Each Pylon has a different function and abilities. Some control different aspects of the Land, such as the movement of the Sun and the Moon, others act as time portals.
Most Pylons contain a "Matrix Table" filled with Crystals, these are the power source and aspect modifiers. Nearly all Pylons have a hand-sized tetrahedral "key" projecting from about two thirds of the way up one side; when turned, a diamond-shaped patch of the Pylon's surface below it dematerializes to provide a small doorway inside. Apparently, some pylon keys can be removed from a pylon by shining reflected sunlight on them, sealing the Pylon, and can be replaced by pressing the key back on the Pylon's surface. The interior of the Pylons is an extra-dimensional black void with no discernable boundaries or surfaces and is significantly larger inside than the Pylon appears from the outside.
At least one Pylon, the Sun Pylon, features a circular hatch that can be opened and closed with the aid of a special blue crystal "key". It is the only Pylon which is known to be directly above the Lost City tunnels and the only known black Pylon.
Pylons are part of the fundamental infrastructure of the Land of the Lost; when the light crystals on their crystal matrix tables are tampered with, all manner of effects on the Land can be produced. Examples include causing storms, opening and closing time doorways, triggering earthquakes, and even manipulating the rate at which celestial bodies travel through the sky. Pylons appear to have specialized functions; a "Weather Pylon" controls rain, a "clock Pylon" controls the movement of celestial bodies. The synchronization of the pylons with heavenly bodies is also seen in "Pylon Express"; one pylon only opens when the three moons are aligned.
- In Season 3, the Pylons were redesigned after many of the original sets were destroyed. The new Pylons were dull in color and the interior had clearly defined stone walls and floors with a mica-like appearance. Likewise, the matrix tables were redesigned with a stone pedestal and a grid of all-red crystals.
- The episode "The Possession" presents the idea that the Pylons were built by the Altrusians. In David Gerrold's backstory for the series he confirms this, explaining that the Altrusians built the entire Land and everything in it as a way-station intended to let travelers cross between various places. The time doorways are gateways which allow their users to cross into the Land on their way to their destination. The reason that travel through the time doorways is unpredictable, at best, is that the Land has fallen into disrepair in the time since it was built. However, the series as presented remains unclear on this subject.