The Small Gallery is for games that support 28mm-scale. We used inch system (2,54 cm) but our cell is 26 x 26 mm. It was selected for convenience and goes well with most of the standard minis. The product is modular and compatible with all of our terrain including the Castle and the Deep Dark Dungeon.
The assembly instruction can be found here - http://towerrex.com/
To put this terrain together you don't need glue or hammer.
We create our products with very high precision and user-friendly assembly system.
But we would recommend you to add a little bit of glue on the joints.
This product is flat-packed and ready for assembly.