The historic heart of Monaghan. The Diamond is the wide, lozenge-shaped market square that gives Ulster plantation towns their characteristic plan — a Scottish layout transplanted to Ireland in the 17th century. At its centre is the Rossmore Memorial, a Victorian Gothic stone fountain raised in 1875 in memory of the 4th Baron Rossmore.
Around the square is a coherent ring of 19th-century commercial buildings — the kind of solid mid-Victorian Irish shopfronts that are slowly being lost in larger towns. The Westenra Hotel takes up the south side. It's worth a slow lap before heading on to the museum or the cathedral.