You will need

-Matches
-Glue
-Working space

Step 1: Tower Base

Put 2 matches about a match width away from each other. Stick 8-10 on them in a perpendicular direction, add another layer like this.

Step 2: Tower Walls

Add 20 levels of matches perpendicularly of 2 per level. Like this.

Step 3: Tower Top

Add another level (the floor) of about 8-10 matches and another 4 levels of 2 the end result is this.

Repeat these steps another 3 times to make 4 towers.

Note: Sorry the image is not the right way up

Step 4: Walls

Put 2 matches about a match width away from each other. Stick 8-10 on them in a perpendicular direction.

Repeat this step 12 times.

Step 5: Attaching Walls Onto Towers

Stick one wall per tower; wait for the glue to dry the stick walls to the already stuck ones with 2 matches (into a 4 by 4 square). Like this.

Step 6: Big Towers Foundation

Put 2 matches about a match width away from each other. Stick 8-10 on them in a perpendicular direction, add another layer like this. The end result should be this.

Step 7: Big Tower Walls

Add 30 levels of matches perpendicularly of 2 per level. Like this.

Note: Sorry the image is not the right way up

Step 8: Big Tower Top

Add another level (the floor) of about 8-10 matches and another 4 levels of 2 the end result is this.
Repeat these steps another 3 times to make 4 towers.

Step 9: Main Building

On paper draw an octagon the edges being the size of matches (except for 4 opposing sides which should be shorter). Place the matches in turns spreading out into a 2 match width length then connect them with matches. Build 20 levels of walls (first 4 opposing sides then the next)Like this.

Turn it upside down