[5] Monaghan County Council's preferred interpretation is "land of the little hills", a reference to the numerous drumlins in the area.

The Menapii Celtic tribe are specifically named on Ptolemy's 150 AD map of Ireland, where they located their first colony – Menapia – on the Leinster coast c. 216 BC.

[7]: xiii  The partition of Ireland in 1922 turned the boundary with County Armagh into an international frontier, after which trains were routinely delayed by customs inspections.

[7]: Map 39 In February 1919 the first self-consciously proclaimed soviet in the United Kingdom was established at Monaghan Lunatic Asylum.

[8] This led to the claim by Joseph Devlin in the House of Commons of the United Kingdom that "the only successfully conducted institutions in Ireland are the lunatic asylums".

[10] It was detonated outside Greacen's public house on North Road in a car that had been stolen earlier that afternoon in Portadown, Northern Ireland.

[11] It also injured scores of civilians and caused extensive damage to the fabric of the town with North Road and Mill Street among the areas worst affected.

A monument in memory of the victims was unveiled by the eighth President of Ireland Mary McAleese on 17 May 2004, on the occasion of the 30th anniversary of the atrocity.

The sandstone and metal column containing seven light wells bearing the names of each of the seven victims of the bombing was designed by Ciaran O'Cearnaigh and stands as a reminder of one of the darkest days in Ireland's modern history.

The museum is located in a mid-Victorian stone building of three stories, formerly two separate town houses, on Hill Street.

[17]: 16 Monaghan is notable for the quality of its nineteenth-century architecture, which adds a sense of dignity to the attractive town centre and its environs.

Of its Victorian buildings, the Monaghan Courthouse on Church Square, designed by Joseph Welland and built in 1830, is the most stately.

With its sandstone facade of Doric columns supporting a pediment that bears the royal arms of the House of Hanover, Monaghan Courthouse constitutes an integral part of Church Square.

Occupying a similarly commanding site on the opposite side of the town is St Macartan's College for boys (from 1840), a 17-bay classical structure with a bell tower and private chapel, by the Newry-born architect Thomas Duff.

One of the most interesting aspects of Monaghan's Victorian architectural heritage, which also includes the former railway station, the Orange Hall on North Road and the Westenra Hotel on the Diamond, is the rounded corners that connect the town's buildings from one street or square to the next.

This practice of rounding corners in order to open up panoramic vistas was carried out with unprecedented frequency in the town of Monaghan, and is still reflected today in the edifices of The Diamond, Church Square and Mill Street, helping to secure Monaghan's status as one of Ulster's more attractive large towns.

There is a campaign to boost tourism by reopening the Ulster Canal in a scheme which would eventually allow boats to travel from towns in Northern Ireland, such as Newry, by way of Monaghan to places as far south as Limerick, as well as Dublin.