Travel
The Road to Oxiana by Robert Byron (1937) remains one of the great travel books in the English language. Byron traveled through Persia and Afghanistan in the 1930s, and his account of the architecture and people is brilliant, opinionated, and very funny. The descriptions of the Friday Mosque in Isfahan and the Gumbad-i-Qabus tower feel as fresh as they did when he wrote them.
Mirrors of the Unseen: Journeys in Iran by Jason Elliot (2006) is the best modern travel account. Elliot traveled Iran over several years and writes with intelligence and warmth about places far off the tourist circuit — the Sistan basin, the borders of Baluchestan — as well as the famous sites.
History and culture
Shahnameh: The Persian Book of Kings by Abolqasem Ferdowsi (written c. 1000 CE, numerous translations) is the epic that forms the backbone of Iranian cultural identity. Ferdowsi spent 30 years composing it. The Shahram Rajabi / Dick Davis translation is the most readable in English. Even a partial reading transforms your understanding of why Iranians feel such attachment to pre-Islamic Persian civilization.
In the Rose Garden of the Martyrs by Christopher de Bellaigue (2004) is the most penetrating account of the Islamic Republic written by an outsider. De Bellaigue lived in Tehran for years and writes with unusual honesty about the revolution, the Iran-Iraq war, and the contradictions of modern Iranian society.
The Persians: Ancient, Mediaeval and Modern Iran by Homa Katouzian (2009) is a thorough and readable history spanning from Cyrus the Great to the present, written by an Oxford-based Iranian historian.
Persian poetry
No visit to Iran makes complete sense without at least a sampling of the classical poets. Hafez (Hafiz) and Rumi are the most celebrated. The translations by Dick Davis are excellent. Iranians quote these poets in daily conversation and can be surprised and touched when a foreign visitor knows even a verse.
Fiction
Savushun by Simin Daneshvar (1969) — often cited as the first novel written and published by an Iranian woman — is set in Shiraz during the Second World War and captures the tension between tradition and modernity with great subtlety.
My Uncle Napoleon by Iraj Pezeshkzad (1973) is a beloved comedic novel about a large Iranian family and the paranoid patriarch who believes the British are behind everything that goes wrong. It was enormously popular in Iran before the revolution and gives real insight into the Iranian sense of humor.