Glasnevin Cemetery is one of Dublin's great historical places, opened in 1832 when Catholic burials were still tightly constrained. Many of modern Ireland's political figures are buried here, including Daniel O'Connell, Charles Stewart Parnell, Michael Collins, and Eamon de Valera.
You can walk the grounds for free, but the visitor centre and guided tours make the history much easier to follow. A back gate links the cemetery with the National Botanic Gardens, making the two a strong northside half-day.