<p>Musicians gather nightly at The Cobblestone, a pub famous for traditional Irish music. Ultra-casual musicians arrive, join in, and leave as they wish.</p><p><em>National Geographic Urban Insider Annie Fitzsimmons and photographer Catherine Karnow set out to explore the best of Dublin. Read about their travels <a href="http://intelligenttravel.nationalgeographic.com/blog/urban-insider/">on the Urban Insider blog</a>.</em></p><p><em>Read more of</em><em> "<a href="http://intelligenttravel.nationalgeographic.com/2014/06/12/the-perfect-day-in-dublin/">The Perfect Day in Dublin</a>" on the <a href="http://intelligenttravel.nationalgeographic.com/blog/urban-insider/">Urban Insider blog</a>.</em></p>