Progress on modular Mordheim board

Remember that Mordheim building I have shown you in the last post? It's actually a part of a bigger project: modular 15mm Warhammer city board. You have probably seen the incredible Mordheim board by Wolfgang. My aim is to build something combining his Mordheim table with modularity of GW's Realm of Battle board.
I've decided to use large 'waffle blocks' (see the picture below), with some pre-cut plywood glued on top of them. Therefore the board will be sturdy yet completely modular, with dungeons and basements below the buildings (the blocks are 5cm deep, so the holes in them can be used as a basis for making all kind of underground passages), a canal system and a number of different building fittings that can be combined in different ways on each tile. Too ambitious? Perhaps, but well - see below:

Overhead view of a simple 60x60 board (4 tiles: building tile with space for 20x20 fitting, buidling tile with spaces for two perpendicular building fittings, two canal tiles)

Another overhead shot of the board.

A canal tile with an unfinished bridge.

A building fitting on one of the building tiles.

When you remove the building, you can put the miniatures into the basement.

20x20 building fitting: Garden of Morr