Harkas Architecture

The Harkas species relies on bioengineering rather than conventional technology to perform the many needs of their civilization. As such, all harki structures would need to be producible by purposed organisms. When the harki were created and their knowledge of bioengineering was primitive, they initially relied mainly on large caves for shelter. As their understanding improved, they have been able to construct shells by making some shelled creatures grow to larger sizes. Though these could be placed mostly freely, they took many years to build and required a huge amount of food to build. They might also need materials like calcium to repair if damaged...

The harki also have hands, allowing them to manipulate. Over time, they learned to construct their own shelters inorganically which took a lot of work to perform. They could not move but could be placed somewhat freely. 

In later periods, they eventually invented purposed organisms that could construct large structures almost completely autonomously. Making use of huge swarms of a purposed bacteria, they could create the needed organic materials themselves and used pheromones to communicate complex construction schematics. Their food requirement was even quite low as they could be made dormant when not in use, but they would require a number of construction managers in order to guide the microbes to construct the building correctly.

The many subspecies of spaceborne harki have a vastly different architecture though. They would also initially live in caves formed in huge asteroids in order to hide from predators but the requirements of that made these types of caves quite slim. They have probably tried building homes into larger fauna shells, but this would make their homes move along with the creatures they are attached to, and they might migrate without warning. This has permanently split more than one family in history though, so this quickly became obsolete. They instead learned how to manipulate other creatures to fight off the predators for them, allowing them to inhabit entire asteroids including the outside. This has rapidly increased the amount of resources they could use, allowing them to create larger and larger purposed organisms for more effective self defence. Eventually, they built creatures large enough to exceed that of the predators, turning some into bioships. 

With modern technology, they are still seen sometimes inhabiting asteroids, but they can now grow large stations using a somewhat similar purposed bacteria that the surface harki use for construction now. They would also need to radiate heat though, justifying the need for several species of purposed organism to work in tandem. 

Specifics of cultural architecture differs between cultures, but some would decorate their structures with colourful inorganic materials, some with live purposed organisms (often for bioluminescence, though some might make use of eternally changing 'living structures'), sometimes they would construct their buildings in a way that is interesting, despite the sheer inefficiency of the latter scheme. Some highly militaristic cultures might have desired to defend themselves very effectively and have essentially made every structure a fortress.