Every time a death penalty is commuted or a government repeals the death penalty anywhere in the world, the Roman coliseum is lit up. The initiative originated with the Community of SantEgidio.

The colisseum is notable as having served for centuries as a site for public executions of various kinds. This is an example of an historical site being used to mobilize sentiment for values exactly the opposite of those it was originally built to promote. Where once thousands were executed in front of cheering crowds, a ceremonial lighting draws smaller crowds of anti-death penalty activists and various dignitaries. To mark the abolition of the death penalty in New Mexico, the governor of that state came to Rome and met the pope and anti-death penalty activists and even a few citizens of New Mexico who happened to be in Rome and heard about the event.

http://www.democracynow.org/2009/4/20/gov_richardson_activists_honored_in_rome