I really like the Dungeon Terrains but they require a lot of material and printing time.
So I decided to resize them a bit and to block them I used the LEGO bases.
For the upper part I recycled some models taken by other users of "thingiverse", I honestly do not remember them all, but some certainly belong to the OpenForge series by Devon Jones.
Those in the picture were printed with a resolution of 0.3mm and upside down to ensure effective locking, I recommend a higher resolution to correct all visible irregularities.

Passages and openings: https://www.thingiverse.com/thing:2803272
Stairs and Columns: https://www.thingiverse.com/thing:2803355