Liege Maximo's tomb

Weren't the Thirteen supposed to be bigger?

Liege Maximo's tomb contains the remains of, well, Liege Maximo.

Fiction

Prime cartoon

Megatron visited the tomb with Dreadwing to remove Maximo's arm, which would allow him to use the Forge of Solus Prime. With the arm, he used the Forge to craft the Dark Star Saber. Alpha/Omega

The Covenant of Primus

After the death of Solus Prime and the uncovering of Liege Maximo's treachery, the remaining members of the Thirteen battled his creations and when it was over, Onyx Prime was mortally wounded, the others were injured in varying degrees and Liege Maximo had been torn apart before being killed with a shot to the head by the Requiem Blaster.

For their beloved Solus, the Thirteen built a beautiful tomb and set it in a portion of space where the most magnificent nebulae could be seen. For their treacherous brother, the Thirteen stitched together what they could find of his remains and built him a resting place deep in a gorge, where it would be built upon and forgotten. Alpha Trion would later comment on the irony that in life Liege Maximo had used Megatronus as part of his schemes, and many ages later one of Megatronus's descendants would hack off one of Maximo's arms as part of his own plans. Covenant of Primus