Here is some groundwork for a 4th Age campaign I've been thinking about:
It is as if the Dark Lord still haunts his land. It is known that his servants certainly do. Orcs, Trolls, and various factions of evil Men vie for the control of the remnants of the great armies of Mordor. Ghosts, both of Sauron's servants and his enemies - many of whom endured great and long torment in the bowels of Barad-dur - walk this dark land also. Wargs and even fouler creatures roam Mordor, directionless with Sauron's passing, but ruthless and deadly nonetheless. It should also not be forgotten that strange and horrid things still haunt the Ephel Duath, ready to pounce upon those who enter the dark land of Mordor.
Gondor has built a small fortress near the ruins of the Dark Lord's fortress. It is there to guard the ruins, provide a base for expeditions into those ruins, and to be a picket in case any remaining servants of Sauron decide to congregate in force.
The fortress was built using stone hauled in from Gondor. This is because the few remaining keeps near Barad-dur that were intact after the fall of Sauron were so infused with evil that not even the hardiest Gondorian garrison could long abide being in them. Headaches, nightmares, and a general malaise sapped morale. Troops returning from their tour of duty in those places were listless and depressed for months afterward.
King Elessar, concerned for his soldiers, but wanting to ensure that the ruins of the great fortress were not looted by evil beings looking for some of Sauron's powerful artifacts, decided to have a small castle and keep specially built. Dwarves were hired to assist engineers from Minas Tirith, and Durin's folk seemed grimly pleased to be building a fortress in the very face of the Dark Lord's seat of power. Good, clean stone was shipped in great caravans, and the building of the fortress took less than a year.
Teams of explorers, specially commissioned, are examined by the King himself to determine their trustworthiness. They are then sent to various parts of the ruins of Barad-dur, based on their training and experience. So far, only some few pieces of Sauron's vast treasury and armory have been discovered, most of which was so tainted as to necessitate destroying them. Yet the King richly rewards those who return with such items. It is known the King takes a keen interest in the discovery of the palantir once used by Sauron. Though it is now so touched by Sauron's evil as to be worthless to any sane person, the King does not want such an artifact to fall into the hands of Sauron's one-time servants.
There are some few bold adventurers who prowl amongst the ruins outside the approval of King Elessar. Mordor is a vast and darkened land, and the ruins of Barad-dur are also large and spread out. Even the largest, most alert garrison could not prevent the trespass of all those adventurers who sought the ruins. Some come simply to line their own pockets, but many of Sauron's minions covet the wealth they know to remain in the shattered fortress. These miscreants slip amongst the shadows, endeavoring to elude the alert garrison of Gondor.
