What's the first thing you do...

...when you look at a map?

You try to place yourself on it, or at least where you live, or if not that, then somewhere you've been. That seems to be a general rule, to judge by the people who were at the British Library's Magnificent Maps exhibition on Bank Holiday Monday. People from all over were poring over the maps on display pointing out to each other places they knew.

But the range of the exhibition was much broader, more imaginative than it might sound. From the mediaeval mappa mundi to the present day, there were examples of maps (almost all from Europe) as artefacts for religious contemplation, as conspicuous display for monarchs to overawe visiting diplomats or to remind neighbours of their vulnerability, as news reports of great victories, as speculative indicators of wealth to be gained as well as charts of seafarers' waypoints and friendly harbours (never mind about the hinterland), as political satires and propaganda, before we got anywhere near the conventional instructional maps we know today. It was a useful reminder to see them in a context that underlined how much subjectivity there can be in choosing what to represent, and how to do so.

I shouldn't have gone on a chilly Bank Holiday - half the world seemed to have had the same idea. But since it's free, it would be worth going back on a quiet weekday morning - the star attractions included Stephen Walter's The Island, a combination of local and personal London lore that one could spend all day on. There's a world map of facts and fancies to do with tea, that I think I remember seeing as a child, and that I wouldn't mind looking over again. And I'd like to spend more time on Grayson Perry's personal take on a mappa mundi, the Map of Nowhere: here the conceptual relationships of various places in the known world to Jerusalem or Rome are replaced with so many concepts floating around in public discussion, media cant and boilerplate artspeak: