Merrion Square is a Georgian square on the southside of Dublin city centre. It was laid out after 1762 and was largely complete by the beginning of the 19th century. It is considered one of the city's finest surviving squares. Three sides are lined with Georgian redbrick townhouses; the West side abuts the grounds of Leinster House (seat of the Oireachtas), Government Buildings, the Natural History Museum and the National Gallery. The central railed-off garden is now a public park.

The Wellington Testimonial to commemorate the victories of Arthur Wellesley, 1st Duke of Wellington, was originally planned to be located in Merrion Square. However it was built in the Phoenix Park after opposition from the square's residents.

Until about the 1950s, the houses in the square were largely residential, but today most of them are used for office accommodation. The Irish Red Cross, the Central Catholic Library, the Irish Traditional Music Archive and the Irish Georgian Society have their headquarters on the square. The poet W. B. Yeats lived at No 82, and Daniel O'Connell at No 58, now home to the Keough-Naughton Center of the University of Notre Dame. 

The National Maternity Hospital is on the North terrace. A number of houses in the square have plaques with historical information on former notable residents, including A.E. (George William Russell) and Sheridan Le Fanu.