Can't Remember How To Duplicate a Building Design.

I’m working on creating a town square for a book scene, hostels and casinos etc. For this, some of the buildings will be very similar if not identical.
A few months ago I participated in a UE4 workshop and I remember working on something like a blueprint that allowed me to use multiple different actors/pieces and create a design that I could place in the landscape without having to continually recreate it piece by piece. Unfortunately I can’t remember what it’s called or how to access it.

Any help figuring out what it is and how to use it, or a similar feature would be greatly appreciated.

There are a few ways to do this but you mentioned blueprints.
A blueprint can have multiple static meshes added as components and then you can place multiples of this blueprint as actors in the world and from there each one can have variations, or you can make different blueprints for different buildings.

Not sure what is best for buildings but That’s one way to do it.

along with what mightyenigma said you can select all the parts of your building in your scene and then right click and say convert to static mesh, or you could group them in a similar manner. the difference there is that in one case they become one item permanently in the other they are just grouped up but are still individual items. there used to be a way to convert to bp but now it seems that can only be done to one item at a time not to a group of meshes.