1. Having or appearing to have only one colour.
2. Of or composed of radiation of only one wavelength: monochromatic light.
3. Done in monochrome: monochromatic paintings.
4. Exhibiting monochromatism.
5. Unvarying or dull: “the more prosaic and monochromatic aspects of communist life” (Amy Tan).

This is detail from the sea wall at Helmsdale, a town that sits on the edge of the North Sea and the river estuary from which it takes its name (or vice versa).  The major A9 trunk road through the town once took a circuitous route through its streets, crossing the river by an elegant stone bridge.  A concrete bridge that would suit any motorway, anywhere in the world, now swoops across the mouth of the estuary in a single bound, by-passing much of the town.  The peace that has descended on its streets is probably welcome by many of its residents but perhaps not so much by its traders.  The golf course has seen better days and the talk at other clubs was of financial collapse. Its destiny may have been determined by the arrival of the dull, monochromatic bridge.

The first of these images fits the bill but the second, less so. I must learn to stop dabbling with saturation:

Monochromatic ... Monochromatic ...