A new exhibition opened at St Patrick's Cathedral in Dublin today, to mark the centenary of the outbreak of World War I.

The centrepiece of the 'Lives Remembered' exhibition is a steel sculpture called the 'Tree of Remembrance', which is surrounded by barbed wire.

People can tie their own messages to the tree, to remember people who have been affected by any conflict situation.

The exhibition will remain open at the cathedral for the next four years.