I thought of building a wall to stop mobs from coming in but enderman are frequent annoyances and seem to take pleasure in taking my work apart. How do I stop them without having to disable achievements?

2 Answers

As on the minecraft wiki,

Endermen can pick up these blocks, if you build your walls out of something not listed here, such as Cobblestone, they can't pick it up. Just remember they are able to teleport into your base through the wall.

How do I stop them without having to disable achievements?

Well, your question is tagged as being java edition, which still displays 'advancements' even when cheats are allowed. You could disable mob griefing with the /gamerule command.

Or, if you are on a server, I am pretty sure there is a flag for this in the server software's .yml main config file.