Stronghold

A stronghold or commonly referred to as an End Portal is commonly known as a gateway towards entering the End dimension. Introduced in Beta 1.8, there were only three in the Minecraft world prior to 1.9. However, since 1.9 there are 128, and this is the amount of strongholds there are on the server (since the server has Minecraft 1.12.2).

Closest Stronghold to Spawn
The closest stronghold to spawn is widely used by the 9b6t playerbase. It can be accessed using a nether portal on a branch of the X+ nether highway. The portal is currently inside an obsidian room due to constant griefs destroying the rest of the stronghold and island above.

Other Strongholds
There are approximately 10 other strongholds spread out around the greater spawn region. These can easily be found by inserting the world seed into a stronghold finder. They have been used in the past as stashes for the donkey/end portal dupe. Most, however, are still widely ungriefed and unexplored.

Here is a table of all strongholds on 9b6t: