Service revived the Harcourt rail route
The old Harcourt Street railway, on which much of the Green Line now runs, was shut in 1959 under a policy to close routes deemed unprofitable.
Harcourt Street station, now the Odeon bar, had been built a century before.
The original line opened from a temporary terminus on Harcourt Road on July 10, 1854, and ran as far as Bray.
A permanent terminus was opened at Harcourt Street five years later. A 2012 TG4 documentary tells the story of the line.
Two companies competed for the contract to operate the service, with one laying the tracks from Harcourt Street and the other from Bray.
The first to reach Dundrum would win the contract. The successful bidder was William Dargan, after whom the Luas bridge in Dundrum is named.
After the closure in 1959, the route was preserved. The old railway line to Bray had 'dance' trains filled with excited young people.
They were allowed buy a ticket to the town that gave them access to the Arcadia Ballroom as well as their return fare to Harcourt Street.
As well as reviving the old rail route, the opening of the Green Line marked the return of trams to the city.
The previous tram system began operating in 1872, with most of it eventually coming under the control of the Dublin United Tramways Company (DUTC). At its peak, more than 97km of track was in use and profitable. By 1901, the old system with its 280 trams was electrified. In 1911, the network had 330 trams.
With buses becoming more popular, the DUTC closed its last tram route - the number 8 to Dalkey - on July 10, 1949. Gardai had to be deployed to protect the carriage from souvenir hunters.
The Hill of Howth Tramway, operated by Great Northern Railway, was transferred to CIE in 1958. It closed in May 1959, becoming the last tram to run in the country until the Luas system opened in 2004.