Keep an eye out for these yellow discs, currently decorating the lamp posts of Southwark. Each is a sign that something noteworthy happened nearby, and will point you to a mobile web page where you can read all about it. The idea comes from a company called City Insights, who are piloting the scheme at 40 locations in SE1 as part of the London Festival of Architecture.
As high-tech tourism goes, it's rather low-tech - refreshingly clear of fancy GPS or augmented reality 'solutions' that make similar history apps too temperamental. Just call up the City Insights web page and type in the code on the sign. This simplicity means that even the most basic web-enabled phone should be able to cope. The content is pretty decent, too, covering aspects of the area that even locals will have missed.
Southwark seems to have a hidden agenda of lamp-based crypto-orientation. Famously, the route from Southwark station to Tate Modern is demarcated by a trail of orange lamp posts.
The discs will be hanging around until the end of July.