The Natural History Museum — affectionately known to Dubliners as the Dead Zoo — is a Victorian museum frozen in time. Opened in 1857, it has barely changed since: glass cases packed with taxidermied animals fill every inch of the galleries, from Irish wildlife on the ground floor to worldwide specimens above. The Irish Room contains the skeleton of a giant Irish deer (Megaloceros giganteus) with antlers spanning 3.7 metres.
Entry is free, and the museum's very lack of modernisation has become its greatest asset — it is a perfect, if unintentional, museum of how museums used to be. Avoid the temptation to rush; the upper galleries, accessed by a narrow spiral staircase, contain some extraordinary specimens.