Space Voids are areas in the universe that are for the most part, empty. They lack stars, meteors and black holes; They are simply put, the lack of celestial formation.
Considering that future universal empires may want to build super large space stations the size of whole solar systems; would Void Space be a good area for building them?
No
The Solar System is really tiny compared to the scale of a galaxy. Space Voids, specifically Boötes voids are areas where the density of galaxies is less than normal, and space stations the size of our solar system would not give any visible benefits. The optimal locations to establish a space station would be just outside a galaxy or in one of the arms of a spiral galaxy, as this gives access to the galaxy, yet is devoid of large unstable celestial activities which you might find closer to the center.
Cosmic voids are the vast empty spaces between filaments (the largest-scale structures in the Universe), which contain very few or no galaxies. The further you go from the galaxy, the harder it would be send the huge amount of resources need to build the station. A space station in the void would emit a lot of IR radiation, making it easier to observe, track and attack. A real life analog would bases in the Antarctic and Arctic.
Building space station along the filaments allows for greater access to resources, access to galaxies, and makes them easier to reinforce if attacked. There are a few exceptions to this:
Voids would be a terrible place to build anything, since you would have essentially no matter or energy to work with in order to build. You wold have to import everything, which would add to the expense of building and operating whatever it is you are doing.
In a military sense, this is a bad idea as well. Your structure, being the only thing in the void, would be quite easy to pinpoint and target by a hostile party or civilization. Nothing like having RKKV's swarming towards your isolated outpost. And of course fighting back would be difficult, since you would not have the "home field" advantage of a star or black hole to power your civilization and defences.
The only potential reason to do something like that is you need the coldest, stillest place in the universe to conduct some sort of experiment, and being in the heart of the void makes doing the experiment much easier.
To give you an idea of the scale, if the Böotes void was the size of the Gobi desert (800 km across), our solar system (measured all the way to the Kuiper cliff) would be about 4 μm, the size of a typical bacterium.
If our sun was at one end of a football stadium and the next closest star system (Alpha Centauri) was at the other, a space station the size of our entire solar system would be 3.6 mm, roughly the size of a peanut.
The only thing that cosmic voids have going for them is an abundance of empty space, and there is plenty of that right here inside our own galaxy.
The question itself virtually gives the answer itself. Namely, space Voids are areas in the universe that are for the most part, empty. So you want to build super large space stations the size of whole solar systems. Where the Voids lack stars, meteors and black holes; They are simply put, the lack of any materials to build anything. Let alone super large space stations the size of whole solar systems.
Besides Void Space is a long, long, long, long, long, long from anywhere, so unless you want to build holiday resorts where you can getaway from everything, but it would take a long, long, long, long, long, long time to get there. To say nothing of a long, long, long, long, long, long time to get back again.
Therefore, would Void Space be a good area for building them? Answer: no way.
The key unknown in this question is: what is the purpose of the station?
If the station is to be used for ship repair, as a commercial centre for trade, or as a staging location to launch an attack is is unlikely to hold any value being so far from resources (materials or human).
However there are a few reasons why you might prefer to build you space station so far from everything:
These are just to give you a taster of the kind of reasons I plan on building my gigantic space stations so far from home!
It depends on the technology scale and the objectives of the builders. When civilizations get to the point where people are blithely hopping from galaxy to galaxy for vacation, then the intergalactic voids become much like the various intragalactic voids would have been for a star-hopping civilization. They're off the beaten path with relatively little chance that anyone is going to stumble across you by mistake.
So, if the goal is to build something hidden in secret, a void is definitely one place to do it. You will have to disguise all the materials you're shipping out into the middle of nowhere, since there's nothing out there to work with. If the goal is just to have space to work... well... unless you're building an artificial galaxy, there's no need to go out that far.
I'll echo the rest of the answers with a twist: NO. Its a horrible place to build your station, unless you have a specific need for that isolation.
Space stations serve a purpose: Anchorage for your ships, trading hubs, research stations, etc. For most of these purposes you need a station that is economically viable.
Voids are as empty as space gets. This means that during the construction of your station, you basically have to ship everything in. You can't just set up a materials manufacturing center and start mining asteroids for metals, you can't use local matter to build stuff. You can't source your laborers from that planet you're orbiting. Your engineers can't supplement their rations with produce from passing merchant ships. Nothing. You bring everything you need, at cost.
To make things worse, if you can somehow finance the construction of this space station, no one wants to use it. You military would not want to use this thing as a base. Its far from everywhere they are needed. Militaries don't fight over empty deserts. They won't fight over empty space either. There is simply nothing there to fight over. As far as the galaxy is concerned, you're welcome to keep the void because everything they do - commerce, military maneuvers, research, etc - are done in places that are much easier to get to, and live in.
Merchants wouldn't want to spend the resources to travel to your space station to trade with its crew. Why would they? How many people are you going to cram in there? Compared to the several planets they can stop at, not only to offload goods, but to acquire them to sell at the next planets in their routes. Even if your space station produces something very valuable, and for some reason, you have to set up a manufacturing plant so far out of the way (maybe it uses a lot of hazardous materials), its much more efficient for you to send your own cargo ships to carry these produce to market, and then bring back whatever the station needs. Then again, there are other places within a galaxy where you can set up these facilities in relative safety, so why bother traveling so far to the void?
The only reason I can think of that would make building a space station in a void necessary is if you need to set up a facility so secret, that nowhere in a galaxy is secure enough. As Thucydides said in his response, this space station would stick out like a sore thumb out there. But if you keep the construction a secret, and follow strict Operational Security protocols, you may be able to hide it because no one else would think that anyone is crazy enough to build anything in the void. (Enemy spy A: My source told me that the station was built in the void. Enemy spy B: What? Don't be ridiculous. Which idiot would build anything there??).
So yes, there is a scenario for which you need a station in the void. Of course, for this scenario, there are other more easily accessible and economically viable places in a galaxy where you can build your super secret space station. This is about the only thing I can think of that requires what you're asking.
Perhaps your civilization just wants a way out, so they're searching for a place to test intentional vacuum decay as a possible option for suicide.
EDIT:
Put simply, vacuum decay is what happens when a quantum field falls from a metastable energy level to a stable one. See https://en.wikipedia.org/wiki/False_vacuum for details.
An empty space as vast as the Boötes Void might actually be the safest place for experimentation in this direction; it's the perfect place for it, really, since it would take an unimaginably long time (>115 million years) for the bubble of doom that might emerge to reach anything that matters- provided said experiments are performed near the centre of the Boötes Void. It might be even more interesting for such a civilization to weaponize this, rather than destroy itself with it.
I am, of course, assuming that a civilization experimenting with this would have already developed the faster-than-light travel required to get in and out of the Boötes Void on a reasonable timescale. (After all, it's useless to end the universe if you can't see it coming.)
The only potential reason apart from dangerous science is to have a kind of intergalactic service station - somewhere to stop and get some rest and maybe some fuel on the long jaunt to another galaxy. Even at multiples of Light speed it might take days, months or years to traverse the intergalactic void. The milky way is so far from the Andromeda galaxy for example that you'd need to be traveling 2.5 MILLION times light speed to traverse the distance in a single year, and that's edge to edge. Even the best of friends might want a sit down away from one another after a few months.
Alternatively, another option might be that your jump drive only has a certain range so these stations mark safe protected spots to leapfrog to the next galaxy from. Heck, if its gate style transit, these space stations might be the only way to get to the next galaxy.
As an additional, something the size of the solar system would be ridiculously big. To give some idea how big, Voyager 1 has only just (as of December 2006) left the solar system, and that's something that's currently travelling at over 17 kilometres a second (Source)
Space is BIG.
REALLY BIG
