With the development of commercial Dublin in the 17th century , four new bridges were added between 1670 and 1684 : Barrack , or Bloody Bridge , ( the forerunner of the current Rory O'More Bridge ) , Essex Bridge ( Grattan Bridge ) , Ormond Bridge ( O'Donovan Rossa Bridge ) and Arran Bridge .
They were Barrack , or Bloody Bridge , ( what is now Rory O'More Bridge ) , Essex Bridge ( Grattan Bridge ) , Ormond Bridge ( O'Donovan Rossa Bridge ) and Arran Bridge .