This is the 493rd most frequent Finnish word.
vanhan
"Vanhan" means "of the old" or "old (genitive form)" in English.
In this sentence, 'vanhan' is the genitive singular form of 'vanha', meaning 'of the old'. It is modifying 'talon', indicating possession or association to the old thing (house).
Vanhan talon kattomaalaus on valmis.
The old house's roof painting is done.
Here, 'vanhan' is the singular accusative form of 'vanha', meaning 'an old one' (modifying 'valokuvan'). It describes the photograph being acted upon.
Löysin vanhan valokuvan laatikosta.
I found an old photograph in the box.
The word 'vanhan' is in the genitive singular form of the adjective 'vanha' (old), agreeing in case with 'taiteilijan' to describe the age-related attribute of the artist.