Much of the artwork and art installations celebrating London 2012 is focused around ancient monuments and the countryside. I've previously mentioned Peace Camp in another blog entry, which was one of the art installations set up in multiple coastal locations throughout the UK. In addition, various locations throughout the UK will seen (or have already seen) a life-scale and interactive inflatable Stonehenge. Think Stonehenge in "bouncy castle" form.
The inflatable Stonehenge installation was created by Jeremy Deller, and it has already travelled around the UK a fair bit, but it can still be discovered in the north of England. The installation is known as Sacrilege, and you can discover more about it here: [http://sacrilege2012.co.uk/]. The website also explains where the installation is headed next.
Another art installation featured across Hadrian's Wall, and it takes place this weekend. This installation featured many colourful and pulsating balloons marking out the length of the wall, and it's known as "Connecting Light". The piece was designed by New York-based arts group YesYesNo and Zachary Lieberman, and the artwork aims to describe borders (without barriers). The installation uses weather balloons, and these transmit messages between each other and change the internal LED lights to create multiple pulsating colours.
Update (September 11): BBC have posted a video about the balloons on Hadrian's Wall. For those unable to make it up north to see this in real life, you can watch that here: http://www.bbc.co.uk/news/entertainment-arts-19444991