Solving the Puzzle

Little colored squares piled up,
A motley stack of tiles,
A onetime swath of Roman floor
All broken up,
Dismantled pied mosaic begging
Reconstruction.
Is this the blue of sky or sea?
Minute gradations clue one in
To altitude and attitude,
Like this abscissa tilted up:
The jagged slope climbs, x-is-y,
From blue of sea to blue of sky,
With green beneath and everywhere
Along the way. But wait, surprise!
Before the tree-topped flight reclines,
A red-beige finial extrudes,
A fort from former warring times,
All peaceful now.
And in the harbor--bobbing boats.
The town is next, far more complex:
Tan-ocher jumbles--walls and walks--
Orange roofs, and yellow trim
Intensifying blacks of doors
And windows staring mindlessly.
Such tesserae within the greater tessellation,
Painted chips composed of lesser chips of paint,
Suggest a sort of mad digression,
Endlessly descending down to
Bricks and stonework, shards of glass,
To sand, to grains, to dust, and then
To atoms under fingernails
Demanding reassembly.