The above ground ruins are extensive with much of the outer walls of Fort Nikel still standing. The entrance lies in the center of the collapsed central keep. A bed can be found in the central ruins as well.
A Fine Steel Bow, as well as six steel arrows and two shock-enchanted steel arrows can be found near a skeleton on top of a partially collapsed platform outside of the fort. Near the skeleton also lies a gold and emerald ring and a scroll, regardless of the player's level. Since Fort Nikel is located near the Imperial City and on the road to Chorrol, new players may want to take the time to collect the loot, as they may find it useful.
It's a grand example and one of the few locations where bandits fighting Marauders can be witnessed. Not much loot to be had totaling six chests and seven enemies, but witnessing the two sides battle can be enjoyable.
Near the back of Fort Nikel is a small lake. If examined, a rotten and severed body can be found floating in the water. It is the remains of Nath Dyer. If searched, Primrose Leaves and a letter can be found. However, these items will trigger a quest that can't be completed. The developers probably left this as an incomplete quest.
It is possible that Nath was killed by the bandits living in Fort Nikel. It seems that the letter was meant to be sent to an unknown woman in the Imperial City, telling her to meet Nath inside the town, though apparently he never made it there to have the letter delivered or meet her.