The European summer is getting really, really hot — but can its many historic cities cop the heat?

In a world where the concept of European unity appears to be fraying, there has been one thing Europeans have been able to agree on: that is, it's really, really hot.

From wildfires in Portugal, to the southern Netherlands hitting 40 degrees Celsius for the first time, sweltering weather has had a vice-like grip over Western Europe.

For many of the region’s cities, the extremity of this heat hasn’t been…