You wash your feet at the entrance to Golden Temple because it's the most holy site of Sikhism. 
Golden Temple was my favorite site to visit in India.  I enjoyed it even more than the Taj.  Not just because of its beauty, the flashy gold, intriguing mix of architectural styles.  But because it is living, breathing, through the faith of the people.  People come every day from across the world to make the pilgrimage to this site, to pray, to worship, to bathe, to learn, to listen to their old fight songs and experience the soul of their religion.
I was surprised to find out they take communion, too.  But that's not all, I actually found a lot of similarities between Sikhism and Christianity / Catholicism.  Felt like all of Jesus' teachings, just without Jesus.  In fact, they had a Pope figure, their Guru, but then during one transition, the current Guru named the Granth Sahib (their holy book of lyrical writings by the early Gurus and other saints and poets) as the next Guru!  So now, Guru Granth Sahib holds ultimate power in the religion, and the orginal handwritten book is housed inside the gold-plated temple, in the center of the nectar pool, a highly sacred spot for not only Sikhism, but also ancient Hindu legends and a place of contemplation for The Buddha. The compound also holds their political base and places for pilgrims to stay and eat for free.  Inside and around the temple, the holy texts are from before surnrise to after sunset each day, and if you can't make it to the temple, you can watch the proceedings on television. 
If your interested in learning more about Golden Temple or Sikhism (it's really quite interesting) you can check out allaboutsikhs.com/home.php
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