Stonehenge

I am not sure that British culture has been significantly influenced by Stonehenge.

Stonehenge has certainly become an icon, or shorthand, used to represent "a very long time ago" in popular culture (in much the same way as "We're in London" is represented in films by a red double-decker bus, or "We're in Paris" by the Eiffel Tower). It has also been an inspiration to hundreds, perhaps thousands, of artists, poets, photographers, etc...

By and large, the British public feel that our national heritage needs to be protected, and Stonehenge is often used as a symbol of that heritage, as in this image created by Rescue - The British Archaeological Trust:

And used in a particularly appropriate article here - Rescue react to short tunnel option at Stonehenge

In recent years, the monument at Stonehenge has also become central to many alternative/pagan religions, with groups of Druids, Wiccans, Pagans etc. congregating at the solstices. Whether this proves to be ephemeral or stands the test of time is a question yet to be answered. Personally, I suspect that the stones will be standing long after the last Druid has left the building.