Torun is one of Europe's best-preserved medieval brick cities, and it began as two of them: a wealthy merchant Old Town and an independent New Town of brewers, tanners and masons, with a Teutonic fortress standing between them until the citizens tore it down in 1454.

This self-guided walking tour traces that story across eight stops: a tower leaning 1.46 metres out of true, one of three surviving medieval gates, the merchant houses of Copernicus's family, a Gothic church built deliberately without a bell tower, the monumental Old Town Hall, the cathedral's seven-tonne Tuba Dei bell, the castle ruins and the New Town market square.

It all runs from your own smartphone. No app to download and no physical guide to keep up with: professional audio narration and a written version at every stop, an interactive quiz to test what you have just heard, and a route map. Start whenever you like, pause for coffee, and pick the walk back up when you are ready.