Newgrange Cairn, Ireland
Newgrange Cairn. They take you inside in groups and turn out the light and simulate the solstice sun coming up. Make sure to come in towards the end. This is a very cool place but they don't let you stay long. We realized its ok to miss the first bus back; that gets you a few more minutes. NOTE: they call these cairns tombs which is a misnomer. The burials rarely date to the same period as when they were built. Once you experience it, you know that the structure was used for other purposes like astromony and ritual.