The Grand Canal is Ireland’s most notable artificial navigation and has the most substantial surviving monuments relating to passenger traffic by water of any canal in Europe. The canal was first projected in 1755 but the 127 km main line from Dublin to the River Shannon at Shannon Harbour, County Offaly, was only completed, with the advice of William Jessop, in 1804. The most important of several branches ran to Athy on the River Barrow giving through navigation to Waterford. The canal can be used by barges up to 3.9m in beam. It passes through 36 locks, and crosses the River Liffey near Sallins on the Leinster Aqueduct, a stone structure of four arches designed by Richard Evans. Commercial navigation ceased in 1960 but the main line remains open for recreational use. The towpaths are designated as long-distant footpaths. Films showing the canal in use in the twentieth century are shown in the Guinness Museum in Dublin.
The Grand Canal Company owned five hotels that provided overnight accommodation for travellers on passenger boats. That at Portobello, Dublin, built in 1807 is adapted for education purposes and that of 1801 at Robertstown, County Kildare as a community centre, but the hotel of 1806 at Shannon Harbour is derelict.
A trip boat operates on the central part of the canal from Robertstown. The canal is managed by Waterways Ireland, an all-Ireland agency set up in 1999 under the Good Friday Agreement.