St Laurence's Gate is a barbican, a defensive outwork that stood in front of the town's east gate, built in the late 13th century and raised by two storeys in the 15th. Its two round-fronted towers of four floors each are joined at the top by an arch, and the slot for the portcullis can still be seen under the passage. It is a national monument and one of the finest of its kind anywhere.
The gate is oddly large for the east side of a town whose main traffic always ran north to south. The likely reason is the view: from the top you can see down the Boyne estuary towards the sea, the only point in town with warning of an attack by water. The town regularly holds "Music at the Gate", a community music event led by a local uilleann piper, right beside it.