The entrance path to Liverpool’s new Central Library is a 72-foot-long walkway engraved with famous titles from books, cinema, and music. The white names contrast with the gray granite, and you can’t help but notice a seemingly random sprinkling of red letters hidden among the words.

The red letters form a puzzle, a mystery code purposefully embedded in the pavement to pique the curiosity of visitors. The library has never revealed the answer to the red letter riddle; that’s up to visitors to figure it out. Crack the code by placing all the red letters in order. Together, they form the clue.

Secret codes aside, library itself is a gem of the city, situated between the World Museum and Walker Art Gallery. The magnificent old Victorian architecture is juxtaposed with a modern, renovated space. The collection holds tomes dating back 800 years, including some British gems such as handwritten letters by Queen Victoria, Prince Albert, and Florence Nightingale, and a childhood essay by Paul McCartney.