The National Museum of Ireland in Dublin (Kildare Street) has this unique collection called the Bog Bodies. Bog Bodies are naturally mummified human remains in bogs (or peatlands) of mainly from Europe. Some of them date back to 2400 years, and preserved so well you can literally see what was a person’s last meal just before their death. (Spoiler! it was wheat and buttermilk)
The museum has many archaeological pieces from the prehistoric and medieval Ireland, plenty of vikings stuff and also features pieces from Egypt and Rome. Entrance is free and you can spend a nice couple of hours learning Irish history.
Dublin Medina 