Athenaeum Sanctorum

The Athenaeum Sanctorum is an ancient Cybertronian library, hidden away in Cataclysm Tundra. Spoken of only in legends, it is said to predate time itself and was used by the Thirteen, having been constructed to hold the sum total of all their combined knowledge within.

Prime Wars Trilogy cartoons
As Megatron and his group were presented with a riddle that they could not interpret regarding the coordinates of their next objective, Optimus Primal revealed the Sanctorum was actually real, and that it would likely hold the answers they sought. The group traveled to Cataclysm Tundra, where Perceptor finally cracked the riddle and revealed the location of the library's entrance. Finding a massive hall inside, they began searching for information on the Requiem Blaster and Megatronus's goals, until they were interrupted by an attack from Overlord and Rodimus Cron. The two factions battled for quite a while, doing severe damage to the library while Perceptor continued to try and perform research. Megatron's use of the Blaster to kill Overlord ended up destroying the library and most of its data, with Perceptor only able to save a fraction of the information. Thankfully, that information included hints towards Megatronus's plan and the coordinates of their next destination, the Well of Sparks.