Mount Auburn was established at a time when Americans had a sentimental interest in rural cemeteries. It is still well known for its tranquil atmosphere and accepting attitude toward death. Many of the more traditional monuments feature poppy flowers, symbols of blissful sleep. In the late 1830s, its first unofficial guide, "Picturesque Pocket Companion and Visitor's Guide Through Mt. Auburn", was published and featured descriptions of some of the more interesting monuments as well as a collection of prose and poetry about death by writers including Nathaniel Hawthorne and Willis Gaylord Clark. Because of the number of visitors, the cemetery's developers carefully regulated the grounds: They had a policy to remove "offensive and improper" monuments and only "proprietors" (i.e., plot owners) could have vehicles on the grounds and were allowed within the gates on Sundays and holidays.