Cardinal O'Brien said he would not be joining the conclave to choose a successor to Pope Benedict XVI, saying: "I do not wish media attention in Rome to be focused on me - but rather on Pope Benedict XVI and on his successor."
More top news
Over 40,000 people picked up their packs to take part in the annual marathon in the capital.
The country's voters are concerned about security, the economy, and the 10% unemployment rate.
A pregnant woman and a man suffered "severe discomfort" after someone threw bleach at them from a passing car, hitting them in the eyes.