Final answer:
William Cullen Bryant's most famous poem is "Thanatopsis," a cornerstone of American romantic literature that contemplates death and the natural cycle of life.
Step-by-step explanation:
William Cullen Bryant's most famous piece of work is the poem "Thanatopsis." Born in 1794, Bryant was a romantic poet and long-time editor of the New York Evening Post. Although a respected figure in his time, his fame as a poet is predominantly linked to "Thanatopsis," which he began writing in 1811 when he was just seventeen years old. The poem, which contemplates death and the natural cycle of life within a serene and philosophical framework, is seen as one of the cornerstones of American romantic literature and has been celebrated for its elegant language and contemplative message.
Bryant's work has garnered respect for its thoughtful approach to the subject matter and has been an inspiration for poets of the romantic period and beyond, valuing the reflective study of nature and the individual's place within the universe.