Final answer:
Leonardo da Vinci's The Last Supper is not an altarpiece, but a mural in the refectory of the Convent of Santa Maria delle Grazie in Milan, making the statement false.
Step-by-step explanation:
The statement that Leonardo's Last Supper is the altarpiece for the main church space in Santa Maria delle Grazie is false. Leonardo da Vinci's The Last Supper is actually a mural painting located in the refectory of the Convent of Santa Maria delle Grazie in Milan.
This painting, a significant work from the 1490s, depicts the last meal Jesus shared with the Apostles, highlighting the moment he announces one will betray him. Instead of being an altarpiece, this masterpiece of design and human figurative composition was painted on the refectory's wall, enhancing the dining experience of the monks with its spiritual and artistic presence.