Resonance inside Maryhill Monument (Concrete full size version of Stonehenge). 

You will hear a simple bass drum turned into a bass synthesizer by the acoustic properties of the circle. And no the difference in concrete and stone does not affect this substantially, the effect would be stronger at Stonehenge due to the harder and more carefully shaped stone!

Ball Release Reflections Video

This video shows sound reflections in Stonehenge, illustrated by thousands of infinitely bouncy balls being released in the space. You can see the reflections focusing in the centre.

Solstice Celebrations at Stonehenge over several years

This video shows a number of solstice celebrations at Stonehenge, note music is usually present. 

The Imigea Stonehenge model used within Odeon 

This VR 3D model of Stonehenge was used by Odeon software to recreate the acoustics of the complete sight, and compare the results with the remaining site, theoretical predictions and the Maryhill Monument.

Youtube video of Maryhill

Battle of the Beanfield

Police stop the music. Stonehenge free festival prevented from happening in 1985 by force.

Stonehenge Decoded part 9

Prof. Mike Parker Pearson and National Geographic

Metronome Sync

A similar process could allow brainwaves to sync to music, people to sync to echoes and rhythm, all sorts of rhythmic entrainment. Conversation is rhythmic entrainment, as is singing together.

Explanation of Metronome Sync

This is a kind of entrainment. At Stonehenge the acoustics of the space couple rhythmic musical activity and allow people to become entrained.

Spinal Tap Section

(not entirely serious)