This mod redecorates Dark Brotherhoods lair in Old Mournhold.
Oblivion was the first game of the series I've played, so the first time I saw the place I was rather shocked.
I could not believe that the Dark Brotherhood would agree to live in a place like this, so I changed it.
No longer it looks like it is inhabited by some sorts of lowlife, but now it is rather the quarters of one of the most powerful guilds of Tamriel.
Nothing too fancy though, so it will still blend in very well.

The mod also replaces random assassins with named ones.
They all are a bit different in stats, equipment, race, though most of them are still Dunmer Assassins.
All enemies vary in levels from 23 to 37. They do not have that much of expensive gear, I think there is no real need for that.
Be sure to come prepared since the enemies no longer scale with you.
The mod also slightly changes Dandras Vules.

I would recommend you to use it in conjunction with light enhancing mods, otherwise it might be a bit too dark in there.

Thanks to Rattfink333 for the Tapestry resource