Broadstone harbour's location was chosen for its proximity to the markets and the law courts. Bolton Street was the preferred site, but high land prices and objections from local residents forced its relocation to Broadstome. The Kings Inns, designed by James Gandon, was built opposite the harbour and, like the Four Courts and Custom House, was designed with its frontage on a waterfront.

By 1807 a regular passage boat service was operating to Mullingar. In 1845 the Midland and Great Western Railway Company (MGWR) purchased the Royal Canal Company as they wanted to run their new railway to Mullingar on the land alongside the canal.

Their new headquarters and railway terminus at Broadstone Harbour was completed in 1850. This imposing building, designed by John Skipton Mulvany (1813-1870), was built overlooking the harbour. A pontoon bridge across the canal gave access to the station. The MGWR soon lost interest in the canal business and in 1877 they received powers to close 150 yards of the branch and to fill in the harbour. Which they did to construct a new forecourt for the station. That removed the need for the pontoon, and a new approach road, Western Way, was built by way of the aqueduct. A new quay and stores were to be built on the other side of the aqueduct but that never happened and, with Spencer Dock operational since 1873, boats gradually stopped using the branch.

In 1956 the final stretch of water from the North Circular Road, behind Mountjoy Jail, was filled in. In 1924 the MGWR amalgamated with its rival, the Great Southern and Western Railway. Subsequent rationalisation saw Broadstone as a maintenance depot, with passenger services withdrawn in 1937. All steam locomotives were transferred there in 1954, but when steam locomotion ended in 1961, Broadstone was closed.