A passage tomb is a type of tomb which was common in Ireland in the New Stone Age (4000 - 2000 BCE). It consists of a circular mound of earth and stones into which is set a stone-lined passage way. This leads towards the centre of the mound. At the end of the passage is a chamber which is used as a burial chamber.
Passage tombs were usually built on the tops of hills or mountains, so that they could be seen from a great distance. The passage is often aligned in such a way that the sun shines into the passage at a significant point in the year, for example at sunrise on the winter solstice or at sunset on the equinox.
The biggest and most famous passage tombs are Newgrange, Knowth and Dowth.