Decagon

The Decagon, also known as Autobase, is a fortress-like building on the western perimeter of the city of the High Council Pavilions, located in Iacon. It is the main Autobot control center of planetary security and defenses.

Dreamwave Generation One continuity
Jazz, Prowl and Bumblebee were in the Decagon discussing Optimus Prime's decision to head underground alone to face Megatron after the destruction of the Forum of Enlightenment. Skids alerted them to an incoming attack of Decepticon fighters under the leadership of Shockwave.

The four Autobots managed the battle from the Decagon, sending out marching orders and battle assistance to their troops. Jazz declared the attack on the Decagon as "really stupid" since it was the Autobots' strongest position on the planet. Meanwhile, Prowl wondered aloud if that current attack, the destruction of the Forum, and the disappearance of their leader were all somehow connected.

After the Decepticons successfully invaded Iacon, Prowl's group gathered in the Decagon for one last rousing speech before going into battle with the enemy. The building was presumably destroyed along with most of Iacon when Starscream engaged Cybertron's sub-planetary mechaforming platform.

Live-action film series continuity
The Decagon exists and is surrounded by the area where the Autobase is located, Tyrest, the area where the Tagon Heights are located and the Neutral Territories. It houses a secret war factory.

Beast Wars: Uprising
Decagon was located on the northeastern border of the Tagon Heights, and was one of the cities annexed by the Maximal Command Security Force as part of their neutral "Maximal Nation".

Transformers: War for Cybertron (Xbox 360/PS3/PC)
Following the apparent death of Zeta Prime, an Autobot officer named Optimus took temporary command of the Autobots and led his squad down the ruined Iacon speedway in order to reach the Decagon. There they could use the communications tower to contact the Autobot ground forces. However, Starscream was waiting for them, and attacked. After chasing Starscream from the room, a distress call from Zeta Prime was projected in the Decagon's communications grid. Though it was an obvious trap, the message gave Optimus hope their leader could be rescued.