Map preview on facebook

Preview maps like this are indicated to Facebook by a series of 'meta tags' in the HEAD of an HTML document, for example:

<meta property='og:title' content="Charlbury-Lechlade">
<meta property='og:description' content="A 20mi cycle route planned on cycle.travel.">
<meta property='og:image' content='http://cycle.travel/generated/cards/101313.jpg'>

(The "OG" stands for "Open Graph".)

Only one image can be supplied, whereas OSM maps are actually made up of many images tiled together. We wouldn't want to get into specially rendering images just for Facebook previews, so I doubt we'd want to supply a composite image for this purpose. However, it might be an acceptable substitute to (for example) simply supply the tile corresponding to the centre point of the map, zoomed out one or two levels.

If you think this would be a worthwhile change, the place to suggest it is at https://github.com/openstreetmap/openstreetmap-website/issues , or better still, supply working code at https://github.com/openstreetmap/openstreetmap-website/pulls . I'd recommend you include a link to this question.