Sir Richard Francis Burton 
Personal Narrative of a Pilgrimage to Al-Madinah & Meccah Vol I & Vol II 

Captain Sir Richard Francis Burton’s 19th travelogue is simply fascinating. In disguise and (I’m assuming he’s accurate in this) at great risk to himself, Burton made a pilgrimage to Medina and Mecca. His intimate observations of customs, daily life, and travel in a foreign land are the sort that one sees best through the fresh eyes of an outsider, but normally an outsider would be denied that vantage. (Goodreads)