The Pantheon War left behind countless ruins of the divine realms of gods that were either killed or driven out. Interest in these realms have helped to keep them distinct from the rest of the Plane. The majority of these ruins are found on the Upper Planes and the Outlands. As per the Rule of Three, a planewalker that journeys into these ruins can find great wealth, ancient secrets, and/or a messy death.
Ruins of the Abyss-As you might imagine, divine realms in the Plane of Unending Horror did not last long without their patron. Almost every ruin was either claimed by a new god or Abysmal Lord or swallowed back into the Plane. The one exception was Azzgrat. After Graz'zt was forced to abandon his home, it became a battleground for several of the major players in the Abyss, including Cyric, Demogorgon, Morrigan, and Orcus. Even in the midst of the fighting, Azzgrat was looted of valuables both magical and mundane. Today, the Prince of Shadows has reclaimed his abode, and now wants to reclaim the pieces that decorated it (plot hook)
Ruins of Acheron-The Powers of Acheron remained entrenched in their divine realms as well as they always had. On the other hand, there was a significant amount of fighting in this Plane, although cutters interested in battlefield artifacts will have better luck in the Plane's second layer.
Ruins of Arborea-Arvandor was destroyed in a great blaze at the end of the war. While the forests have begun to grow back, the scars of the fire are still readily apparent. Thanks to interference from Celestials, Arborean nature-spirits, and surviving Elven petitioners, many sites in this realm have yet to be rediscovered, let alone fully explored. Among these sites are the Crystal Palace of Hanali and Gwyllachaightaeryll, the Many-Splendored. Another sought after ruin is the Court of Stars, but the Eladrin have hidden this place too well. Finally, the ruins of Amun-Thys have taken on a life of their own-spawning nearby boom towns in Pelion that won't go bust. Despite centuries of expeditions, the "lost" realm of Nephystus continues to provide new treasures to those who visit it.
Ruins of Arcadia-Arcadia has three sites: the Court of Astrea, the War Glade of Gilmadrith, and Cleverthrush's Workshop. All three sites are under the protection of Arcadia's native Celestials. In order to explore these ruins, a blood needs to get permission from the government of Arcadia in Civilopolis.
Ruins of Baator-When a god in Baator was killed or displaced, the Lords of the Nine quickly and efficiently stripped their realms of anything of even remote value, then allowed to merge back into the plane. One realm that still appears to be active is Hecate's secondary realm on Minaurous. Many cutters believe that Geryon, Lord of the Third, has converted the former site to his own uses, though no one can say exactly what.
Ruins of the Beastlands-Many of the ruins of Krigala contain relics, even fortifications, that date back to the partisan campaign that played out in the latter years of the War. Archeologically, this makes no sense, as the current ruins far supercede the Pantheon War (wise bloods chalk it up to the nature of the layer and leave it at that). Also, pieces of Tir Na Og have drifted into Krigala, inhabited by a few hardy Celtic petitioners. The only ruined divine realm in the Beastlands is the former home of Denier-the Library of All Knowledge, in Brux. The Library has yet to be discovered, and many wonder if the layer has not already consumed it entirely.
Ruins of Bytopia-Large stretches of the Twin Paradises still show the aftermath of the clash of Dwarven and Gnomish war machines. On Dothien, the Gnomes have turned the realm of Callarduran Smoothhands into a memorial for all the War's fallen. Anyone caught poking around Deephome without permission will have to pay harsh music. A better welcome can be found in the fallen Alliance realms in Shurrock-The Watchkeep (Gorm Gulthryn) and Windwrath (Tefnut). While no one here will be trying to put you in the dead book, both realms have been almost picked clean. They've already lost much of their unique characteristics and will soon be indisdinguishable from the rest of the layer.
The Ruins of Carceri-Very few powers that lived in the Red Prison were put in the dead book. Given the nature of Carceri, this isn't surprising. The most significant ruin is from the dead goddess Talona. The Place of Poison Tears is a storehouse of potent poisons and deadly diseases. Unfortunately, these toxins are not contained in any way that's safe to handle, so many would-be plunderers never make it back out. Still, a foolhardy berk can make a tidy profit if she can stay alive after such a trip.
The Ruins of Elysium-After the Outlands, Elysium saw the most fighting of all the Outer Planes in the Pantheon War. The ruins of multiple deities lay scattered across the first two layers of the Plane. Unfortunately, Elysium's Planar Lords assigned a cadre of Kerubim (ie the lowest choir of cosmic entities on the Upper Planes) to stand guard over these ruins. Typically, each Kerub takes his or her responsibilities very seriously, viewing most aspiring explorers as being no better than grave robbers. Those not eager to wrestle with extremely powerful celestials should try exploring the bottom of the Oceanus, as there are several wrecks that can still be plundered if you have the right equipment. Aside from ruins, the other lasting contribution to the landscape of Elysium are the War Memorials. Although the scars of the fighting quickly disappeared, they are far from forgotten. At each battle site, a memorial stands in memory of all the soldiers that perished in that battle. Touching the memorial awakens the memory of the Plane, and the battle plays out right before your sodding eyes. In some cases, the experience can even be traumatic. The most extreme example is the memorial that stands on a ridge of lifeless black rock in the middle of Belierin-the plaque warns you not to remove your hand before the battle is complete, or else you'll fall into a century-long coma. As you can imagine, only Sensates and certain pilgrims come to this memorial.
The Ruins of Gehenna-Several dark gods of the four-fold furnaces died or lost their realms during the War. In most cases, the Loths swiftly scavanged whatever there was of value. There was one exception: Corriegrave, the realm of Math Mathowny. The entire structure was buried beneath the lava of Khalas as soon as Math was put into the dead book. The loth's have made several attempts to excavate Corriegrave, but eruprtions continue to interfere. The only other site of significance is the One-Legged Tower, a piece of the Crawling City that was broken off sometime during the Pantheon War. The Tower hops up and down the slopes of Chamada with unbelievable agility and speed, which makes any attempt to enter the ruin almost impossible.