Compound
A Compound (CP) is a customizable building inside which other buildings can be constructed. In effect, it is a structure used to hold other structures. Many buildings can only be built inside a compound.
Compounds gradually decay over time unless a cornerstone has been installed. Tearing down a compound won't give back materials.
To expand your CP click on the outer border and then choose Blueprints -> Edit blueprints -> Building shape -> Add a sector and finally click on the outer wall. Note that after these steps you must load materials for actual expanding your CP and in the mean time you are not able to maintain or create new buildings in your CP.
Source
Requires Compound Construction from the School of Architecture
Cost
Initial 3x2 compound:
Compound Expansion (varying amounts of the following depending on design):
Use
All indoor buildings need to be placed in a compound.
Tests
Principles of Architecture requires a compound to be built and expanded to 16 sectors to pass. A sector is 16x16 cells.
Types
Town House
- 50 Maximum Cells
For every test of architecture you have passed (up to 7) you can expand a compound an additional 14 cells (for example, if you have passed one test, you can expand a compound to 64 cells, and if you have passed two tests, you can expand a compound to 78 cells). You do not need to own or have built the compound, and can expand any number of compounds. You do not need to load the materials yourself, so it is perfectly viable for someone else to invite you to expand their compound - they set it (temporarily) usable by anyone, you edit the blueprints to add sectors, and walk away with no cost to yourself. They can load the materials at their leisure, and, once done loading materials, also edit the compound to remove sectors or change ceilings, facades, and floors without further intervention from yourself.
Facade
You may not change the facade type on the corners of your compound.