Cain exits the dungeon, keeping all his summons active and inspects the desert around the portal to ensure nobody has come across the location while he was busy. Nothing but unmarked pale sand dunes as far at the eye can see, as if the whole world was sun bleached. 

This honestly seems like the best castle location they could have hoped for. There are dungeon entrances, an underground city entrance, nobody to bother them, and an abundance of building materials, also known as sand and stone that the Elementals can turn into a castle.

The more he looks around, the more of the dark colored stone he finds, the ruins of the old civilization brought either from deep underground or somewhere far away. Cain and his summons haven't found anything like it in the area. 

"Granite Elementals, call for as many Earth Elementals as you can." Cain directs his summons. These were only Greater Golems to begin with, much less formidable sorts and certainly not as strong as the boss Granite Elemental was, but upgraded by his skills they're Epic Quality. 

Looking through his logs he finds that these Greater Golem versions of the Granite Elemental were the ones that accompanied the Diamond Elemental. Those ones were elite versions, but still recorded as Greater Golems. 

They each Summon four lesser Earth Elementals, which is a good start to a construction force, so Cain starts drawing out a castle layout, based on the surroundings and what he knows of Castle warfare from strategy games and human history.

A Star fort, Eight Points with four larger arms at the cardinal directions seems like the best bet. Placed properly, the entrance to Muzz, the underground city, will be in the East Arm, while the portals will be in the South Arm, leaving a large area for a central keep, plus plenty of room for additional buildings and fields. Cain's idea for that is to have the Elementals and his Oath Breakers reconstruct the old buildings of the ancient settlement as much as possible, filling in only where necessary with closely matched Granite, keeping the weathered details and ancient layout, but contained within a secure fortress wall.

Being in the desert it needs to be self sufficient, which means large, which also means it's going to take some time. Time he already spent in the dungeon. He's definitely not making it back today. 

"Alright Elementals, here's the plan. I want solid basalt walls in this pattern on this scale. See where the portals are?" They make a grinding noise Cain assumes it's an affirmative, so he continues. 

"Make the walls five meters thick at the top, twenty meters tall, and expanded out at a fifteen degree angle on the inside wall with stairs at these locations. I want battlements that look like this, see the way they're angled? We will work on the interior of the castle afterwards." Cain gives the directions and the Granite Elementals start casting some sort of spell, creating an outline of the eight pointed Castle walls with the larger triangles at the ends, giving room for a defense force at the first point of impact by a charging army.

The ground is rumbling and the shining lights are solidifying into a low wall of nearly black basalt, slowly rising out of the sand. The Lesser Earth Elementals have added their magical might to the effort now, and the walls are rising a few centimeters a second. 

Cain gives a short thanks that he drew the very best diagram he could, complete with staircases, because the Elementals are raising an entire castle wall in one piece. 

If this is how higher level cities build and repair defenses, no wonder they're not worried about being overrun. A thousand seconds is Cain's estimate to have the walls raised with 16 Epic Granite Elementals and their assistants. A mere 17 minutes.

At this rate, he had better start drawing the inner fortress and any other additions, including the basic design of the underground labyrinth and the water cistern to keep everything fed. 

"Oath Breaker, how deep can we go before there is interference with the underground city?" Cain asks. 

"About a Kilometer before you get close to weakening the highest points of the roof. More on the south side, which is almost past the edge of the city cavern." The Demon answers helpfully.

That's a relief. Putting a seventy meter deep cistern thirty meters underground should be plenty far enough to keep surface events from damaging it. Then Cain draws an elaborate series of rooms comprising four different levels to link the surface to the cistern, all starting from the basement of the new central keep. 

The walls are long since completed by the time he has his plan drawn and is ready to give building instructions. Ten meter ceilings, ten meters between floors, starting ten meters underground. Done this way, it should all be very solid, at least from what Cain knows of mining. Maybe he should call an actual miner first? 

Cain dismisses one of the Kone Clones and calls for one of the Old Dwarves, the Earth Mages who have spent centuries in the mines.

"Is this safe and stable?" He asks, handing them the paper. The Dwarf makes a number of changes to it with a pencil in his pocket, then alters the design plans for the central keep before nodding in satisfaction at the wall design. 

"Four out of ten. Not quite passable. But the walls look good. The rest should be safe to build now." The Dwarf says gruffly. Unlike the chatterbox of a Dark Elven Priestess, the rest of his Supporters rarely speak unless directly asked a question, despite being capable. They don't have all the personal memories of the one they're cloned from, mostly just skill related memories and some important details remain intact. The clones of Kone do share some of her personality though, they love cuddly things, often leaning against Nemu when they're not busy, or petting the clones of Su.

Cain passes the paper to the Elementals, who proceed to have some sort of conversation with the Earth Mage before getting started.

Cain can feel the ground shifting, and piles of rock are being pulled out of the ground as they go, creating a small mountain in the middle of the castle. It's far too much for the keep and buildings Cain had planned, so he will have to discard it somewhere. Randomly scattered through the sand doesn't sound bad. It might help guide the dunes formation, keeping them from piling up too high within arrow range of the castle walls. 

That is again a job for the Earth Mage, who understands exactly what is needed, designing a series of obelisks and retaining walls at a four hundred meter distance from the castle that will partially block the wind and create a sheltered spot around the castle, with the worst of the sand storms passing over top of them once the dunes build up. 

It would be nice to have some sort of castle sized barrier, but that's a bit beyond their means right now. At least, Cain doesn't know anyone who can do it. 

The sun had gone down and come up again by the time the interior castle structures and basement city as the Old Dwarf called it, are done. The underground levels stretch almost the entire two hundred meters of the central castle yard, enough that they truly could be a city. They're somewhat set up like one. Cain designed clusters of small rooms around central areas that could work as apartments, as well as a system of water and sewage pipes, the latter leading over a Kilometer from the castle to a deep ravine. In time, the sand should filter everything and create an oasis out there. 

For once, the details of some of the city building strategy games Cain had enjoyed in his past life actually came in useful.

Mostly the underground is for future development, Cain just wanted it to exist for now, a deserted maze leading to the treasure vaults he designed into the fourth and deepest underground floor.

In contrast to the black basalt walls and dark gray of the ancient buildings, Cain built the central keep out of solid white marble with a gray slate roof. A square building, with round towers at the corners and many narrow windows to allow ventilation but keep the building secure. The interior floors are mostly white and gold checkered pattern marble tiles, but assorted bedrooms got different colors, a lesson he learned from the design team in Graska. 

The Guild Bank has a lot of leftover furniture items from renovations to their other properties, so Cain sets up a dining room and two bedrooms in the keep, before setting up a Throne they found during the Guild's most recent property acquisition in one of the main floor great halls. Because what is a castle without a throne room? 

The sun has long since fallen and is nearly ready to come up again by the time Cain is done, so he sends an update to the Guild, letting them know he'll be here in the desert for an extra day, and asking how everyone else is doing. 

Most of the answers are as expected, but Cixelcid, Mythryll, Elmira and Lickity have all gone off looking for new arrivals. Lickity and Cixelcid returned together to transfer village, where so many of them arrived. While Mythryll and Elmira went to the starting points in the Elven Forest. 

Their grand plan is to bypass the usual guild logic of waiting to see who snaps from the stress or dies in their first few dungeons and poach promising potential Guild members as soon as they can.

It's an open secret that nearly half of new arrivals either mentally crack or die in the starter dungeon soon after arrival, so even the newest of low level groups usually wait and see for at least ten or fifteen levels until the reality of the transfers situation sets in. The numbers are even worse for arrivals showing up at random in the middle of the Elven Forest. 

The Guild has enough levels and property now that they can have a hundred members, and once Cain has registered this castle he built that should increase even more. So the more new members they can gather, the better. 

Which leads to another thought, the cities have training dummies at their academies that give experience. But where does one find such a thing? 

[Does anyone know where to get training dummies? You know, the ones to have rookies gain experience on while they learn basic skills?] Cain asks in Guild Chat. 

[They're imported from the west side of the continent. Do you want some? The ones that are available come in 3 different level groups, 1 to 10, 10 to 30 and 30 to 60.] Carlos sends back. 

[Get us a bunch of each. It will give the new members somewhere to practice that isn't risking their lives.]

[I'm on it. I'll have a bunch in the Guild Bank this afternoon if you don't mind me using Guild Funds.]

[Use what you need. That's what they're for. We can't have the recruitment officers saying we're not doing anything to help them out here..] Cain laughs to himself as he sends the final response.