Source Wall

The Source Wall was a mysterious, impenetrable wall separating all of space-time from the mysterious source.

History
The Source Wall seems to have been created simultaneously with the beginning of the universe.

Around 13,000,000,000 BCE, the Wall was first charted by the Monitors, and was suspected to have been encountered by several of the early species of the universe throughout its existence.

Mobius incident
In 12,000,000,000 BCE, the Monitor Mobius trying to breach through the wall. During his attempt, he was exposed to the Anti-Life Equation, corrupting him and driving him insane, becoming known as the Anti-Monitor.

Krona incident
Around 10,000,000,000 BCE, Maltusian scientist Krona was performing an experiment on the wall, but inadvertently causes him and his crew of 30,000 to be absorbed into it.

Appearance
The wall held the appearance of a wall of incredible size, taller, lower, and wider, than any other known object in the cosmos. Preserved in the wall are the many peoples who have tried to pierce it, such as many of the Monitors, Krona and his crew, as well as the entire race of Promethean Giants.