The noun serendipity means the phenomenon of finding or discovering valuable things by chance.
Synonyms are fluke, luck, happenstance or chance discovery.
The word origins 1754 from the English author Horace Walpole who wrote a letter to his friend:”I once read a silly fairy tale, called ‘The Three Princes of Serendip‘: as their highnesses travelled, they were always making discoveries, by accidents and sagacity, of things they were not in quest of….”.
Usually we stay in luxury hotels, but this time we took a chance on serendipity and go to a simple airbnb.
There is an element of serendipity in archaeology.
We never plan much when visiting a new city and rely on serendipity discoveries.