Welcome to the Legends of Leiden Treasure Hunt by Leiden Ludens! This hunt is all about the world-renowned alumni of Leiden University. As you travel through town, you will encounter several QR codes like the one you just scanned. They each represent 1 of 7 puzzles related to Leiden legends. You can do the entire tour in one go, or do a puzzle every day – whichever way you prefer! (The QR codes aren’t going anywhere).

Puzzle #5

Kamerlingh Onnes Building


Heike Kamerlingh Onnes (born in 1853 in Groningen) studied at the universities of Heidelberg and Groningen before taking up a position as professor of experimental physics at Leiden University in 1882. In Leiden, he set up the Kamerlingh Onnes Laboratory, which was housed in the building in front of you. Many groundbreaking discoveries were made here. You can read about these on the signs outside the building. Have a good look – it might help you solve the next puzzle…


1. Complete the sequence:
16.80, O.Zr, 4.20, He.Ne, …

2. Who is missing?
C, F, …, R, R

__   __
1     2


Type your answer behind the / in the url. Example: pastatplay.com/youranswer.

This answer must consist of numerical and alphabetical symbols only (no spaces or punctuation marks).