Millmount is the big green hill on the south bank that you can see from all over Drogheda. It is artificial, probably a Neolithic passage grave never excavated, and the Normans built a motte and bailey on top around 1172. In 1649 it was the last stronghold of the town's defenders against Cromwell. A Martello tower was added in 1808, and in the Civil War of 1922 anti-Treaty forces holding it were shelled out by government troops, nearly destroying the tower the locals call "the Cup and Saucer".
The old barracks around the mound now hold the Millmount Museum, which covers the town's long and violent history, and admission includes the Martello tower, whose terrace has the best views over Drogheda and the Boyne. There is a café in the barracks yard.