Clock on the wall. It is self adjusting one by <a href="https://en.wikipedia.org/wiki/DCF77" class="extiw" title="en:DCF77">DCF radio signal</a>.
<a href="//commons.wikimedia.org/w/index.php?title=User:Kacperperschke&amp;action=edit&amp;redlink=1" class="new" title="User:Kacperperschke (page does not exist)">Kacper Perschke</a>
CC BY 3.0
<span class="int-own-work" lang="en">Own work</span>