It is common to see pictures of people at prayer at the Western ("wailing") Wall in Jerusalem. Thousands - even millions - of written prayers are place within the cracks of the wall every year - in a tradition that goes back over 300 years. They are collected up twice a year and carefully buried on the Mount of Olives. The 'Wailing' Wall, however, is only a small section of the the Western wall - the retaining wall built by King Herod the Great to support the massive temple complex built during his reign.
In recent years a tunnel has been excavated along the entire length of the western wall. It is now possible to walk the entire length of the wall through a tunnel beneath the buildings of the old city of Jerusalem. There visitors can see the massive (truly massive) stones cut for the wall, an uncovered Roman road, and a Hasmonean cistern at the northern corner.
And while the visible 'wailing' wall remains a popular place of prayer for people from all over the world, the entire length of the wall is considered holy by the Jewish people and many go for prayer to places along the tunnel.
The power went out as our tour group made our way through the tunnel. We were plunged into darkness for a couple of seconds before the emergency power kicked in. I know that a few prayers went up right at that moment.