Cursed Earth "wonders"
The Cursed Earth Campaign is very different than most of the others so far listed, as it is a pseudo-Post Apocalyptic world with advanced technomagic (think D&D with a Gamma World twist). Also, my elves are invaders from an alternate material plane who are basically the Eldar from WH40K, and have brought the Shadow and it's Taint (modified Rokugan) to this world (which caused the Apocalypse which ended the Golden Age -- d20 Future Urban Arcana, with Technomagic replacing technology). Lastly, to prevent the further spread of the Taint accross the planes, this world has been isolated by the Gods, completely cut off from the astral and outerplanes (but not the ethereal or inner planes, as a world cannot exist without access to the energies of these planes [elements, life, death, etc]), thus clerics have lost ALL powers and the great cathedrals and religious monuments were destroyed by mobs who felt betrayed by their gods and faiths.
That said, here are a few of the highlights so-far created (not sure if all of them qualify for 7 wonders status)
Taintlands -- this is a magical wasteland similar to Eberron's Mournlands combined with Rokugan's Shadowlands, with many of the classic Apocalyptic movie landscapes. Rather than radiation, one has to worry about the corrupting influence of the Taint, which eats at both the physical body and a person's very soul. Living spells (Eberron) and Change Storms (When the Sky Falls) scour the countryside, and aberations of all kinds (which are immune to Taint) can be found here. Even the very laws of magic and the material plane can be warped and twisted in this hellscape, with gravity, light/darkness, atmosphere, etc changing from mile to mile. Only the barbaric Halfling Kins (Dogkin, Ramkin, Bulletekin, Displacer Beastkin, Trollkin, Howlerkin, and Rust Monsterkin), who are also immune to Taint, and the psionic members of the Insect Collective (dromites, thri-kri, etc -- on the Cursed Earth, ALL insectoids are naturally psionic) actually make their homes here. But, great treasure awaits those who are foolhardy and brave enough to explore the Taintlands, as within them can be found the few surviving, intact, and/or unlooted Pre-Apocalyptic structures or caches of "lost" TM technologies/knowledge. The Taintlands actually seem to be receeding over the past millenium, with many of the areas that had been considered Taintlands at the time of the founding of the Federation now be Wild or even annexed and pacified, becoming part of the Federation. Except for a few druids high in the heiroarchy of the Druidic Unified Clades, no one has realized the great secret of the Halflings, that these "primatives" are slowly "terraforming" the Taintlands back into a more natural state through a sophisticated, yet simple, process which involves using magical creatures, among other things.
The Wall -- the Wall defends the Federation (which is the "civilized" TM advanced society with Gnomes [who create most of the TM devices and control the Ethernet], Dwarves [who control the Ministries -- think Imperial China Beaurocrocies], Humans [who control much of the Federation Defense Forces, especially power armored legions with bonded combat drones] and lastly the invader Elves [who control the High Houses and the Federation itself]) from the Wild (anywhere NOT within the borders of the Federation) and the Taintlands. This engineering feat dwarfs even the Great Wall of China, and is heavily fortified. Because of the size limitation placed upon weaponry by the Taint (cannot have any construct larger than small or any weapon larger than an autocannon, HMG, or mini-missile laucher without it almost instantly becoming Tainted and going Christine on you), these hard points are a bunch of smaller "squad" sized weapons rather than heavy artillary and the like. The forces of the Shadow do not suffer from this limitations, with many of the giant pre-Apocalyptic War Constructs and Mecha having survived the last two millenia, along with many more recent Demonic Dweoborgs and Taintmages, and the Wall has been designed to withstand the punishment that modern and futuristic heavy weapons can dish out. Scarred sections of the Wall have even survived nuclear level attacks (although the brave FDF defenders did not). Every century, as the borders of the Federation changes, the Wall is rebuilt, absorbing former out lying forts into its structure and turning the older sections into dwarven warrens and FDF barracks.
Impact Swamp -- within a couple hundred miles of the current Federation borders is the beginnings of a huge swamp (at least the size of the Everglades), which has an unnatural circular shape (the map created for this swamp was a modified NWS downloaded radar image of a hurricaine) and is infested with a surprisingly advanced and strong breed of goblins known as the G'Serrai. Impact Swamp is a post-apocalyptic feature, originally being rolling hills and plains inhabited by the greatest concentration of halflings in the pre-apocalyptic world. About the time of the Apocalypse (record keeping being very spotty from this time), an object hurtled to earth from a rent in the sky and a massive explosion annihilated everything within an area (don't have When the Sky Falls in front of me to figure exact diameter of crater and effect). Even in this time of huge explosions and magical disruptions, the effects of this impact were large enough to be noticed and recorded. It is assumed that the object was the remains of the one orbital habitat or a doomsday weapon run amok. But this is wrong, the truth being even stranger then even the wildest gnome conspiracy theory from the Ethernet. The Halfling gods either saw the Apocalypse approaching or, once it happened, were against isolating and cutting this world loose to survive or not on it's own. So, the entire Halfling Pantheon (including it's less savory members) pooled their powers, creating a gestalt which was barely able to crack through the dimensional barrier, and using the gathered halfling clerics (who had ALL answered the call of their gods to come together) as a beacon, crashed to the Cursed Earth. Out of the destructive maelstrom was born a being that was the sum of a races divinity and spark, the Serrangel. She is the reason why halflings are immune to the corrupting influence of the Shadow and it's Taint, cannot cast divine spells or use any type of divine power, and are on a mission to cleanse the world. A century before my current game begins, the Serrangel was captured and imprisoned at the site of her birth by a cabal of Federation Elves and G'Serrai goblins through the foulest necromantic and corrupted Technomagic techniques.
Thangar's Bar & Grille -- while this probably does not qualify as a "wonder", it is definitely worth a stop. It doesn't look like much from the outside, appearing to be little more than it originally was, a biker bar attached to a small garage. This unasuming structure is where the Dwarven savior, Thangor, fought his greatest battle agianst the Shadow, preventing the corruption of his beloved motorcycle Betsy, and emerging fundamentally changed, his soul being forever more fortified against the Taint. This modest and simple dwarven biker was able to teach others his newly aquired discipline, becoming the prophet and savior of his race in their war against their former servants; the constructs, vehicles, and mecha that fell under the influence of the Shadow. Thangor had become the Saint of the Dwarven Paladins (paladins exist on the Cursed Earth, unlike clerics, but gain their divine powers from their Order and it's Patron Saint, not any god), and his Bar & Grille has become a shrine to dwarves everywhere within the Federation. While the delapidated and belovedly much repaired building may not be a wonder, the sight of hundreds of Paladins of Thangor roaring down the road on their bikes (their equivalent of a Paladin's Mount) in their annual pilgrimage and kegger is awe inspiring.
skippy
GM of The Cursed Earth Campaign