Take US Dollars or Euros with you to Iran and change them up into Iranian Rial at the local exchange offices (not the dodgy guys on the street or at the hotels which have the lower government exchange rate).

Before you know it, you have millions of Rials and it all looks easy. However, while ALL notes state ‘Rial’ there is another ‘currency’ or ‘super unit’ that is used – Toman – which is not listed on any note or coin.

Toman is simply one tenth of the Rial price, so when
Imagine you order the food in restaurant and you are presented with bill of “32,000” which is equivalent to almost $1, unreasonably cheap, in fact the price is in Toman. To convert to Rial, you simply add a zero. therefore it is 320,000 Rial.

Tehran is a cosmopolitan city, with great museums, parks, restaurants, and warm friendly people. It deserves at least a few days of your Iranian itinerary. The city can be roughly divided into two different parts - north and south. The northern districts of Tehran are more prosperous, modern, cosmopolitan and expensive while southern parts are less attractive but cheaper.
At the time of the Zand dynasty, it was a little town that was significant from a strategic point of view. The first of the Qajar kings, Agha Mohammed Khan, named Tehran as the country's capital in 1778, and most of its growth started during the reign of a subsequent Qajar monarch, Fath-Ali Shah. The castle which Agha Mohammed Khan had built was to contain the new majestic buildings. At the same time, the city's populace was redoubled. Due to the increasing significance of the city, gates, squares and mosques were built and it was at the time of Nassereddin Shah that the city's master sketch was prepared and modern streets were constructed. Later, huge central squares like Toopkhaneh square (now Imam Khomeini) and quite a few military buildings were built. Even though the Qajar dynasty was in a period of decline, Tehran soon took the shape of a modern city. The structure of large government buildings, new streets, recreation centres, urban service organizations, and academic and methodical centres were started, even as most of the old gates and buildings were destroyed and the city's old architectural fabric replaced by a contemporary one. Tehran has also earned itself the rather unenviable reputation as a smog-filled, traffic-clogged and featureless sprawl of concrete bursting at the seams with 14 million residents. But you can also find an endless number of nice and cosy places in and around the city - if you know where to look. Tehran is also a city of parks and possesses more than 800 of them, all well-kept. The city is nearly a mile high above sea level and as a result is cooler than other cities in the middle east. Summer temperatures are around 32°C or about 90-95°F. The air tends to be very dry. A combination of factors make Tehran a pleasant place to visit: The dry climate which is constantly cool (at least in the evenings), the proximity of the mountains, the parks and gardens where flowers blossom all through the year, the alleys of trees in the avenues or even smaller streets, and even the water that runs down from the upper city along deep and wide gutters which look like small rivers during spring. The Alborz range on the north of Tehran, which hosts the highest peak in Iran, provides fantastic conditions for ski lovers in the winter. In winter, the mountain hotels and ski-clubs at Shemshak, and Dizine are full several days a week. Some specialist skiers consider the snow value in northern Tehran to be some of the best in the world.

Azadi Tower. has been the longstanding symbol of Tehran. It was constructed to commemorate the 2,500th anniversary of the Persian empire, combines elements of Sassanid and Islamic architecture. The entrance of the tower is directly underneath the main vault and leads into the Azadi Museum on the basement floor.

Tehran City Theater (Tehran Theater of the Performing Arts; Te'atr e Shahr), Enqelab Ave., Valiasr Ave., ☎ 982166460592 ,982166460594. Architect Ali Sardar Afkhami designed the main building in the 1960s, later expanded.  edit
Baharestan. the historic Iranian parliament building, inaugurated in 1906.  

Senate of Iran (Kakh-e Majles-e Sena). Designed by architect Heydar Ghiaï, the construction was led by Rahmat Safai. The dome is one of the most technically challenging projects in the entire endeavor.  edit
Khaneh Honarmandan (Artists' House), South of Honar Park, North Mousavi Ave., Taleqani Ave., Tehran, ☎ +982188310457 (fax: +982188311600)

Tughrul Tower. a 12th-century monument, located in the city of Rey, Iran. Tuğrul Tower is near Rashkan castle.  edit
Rashkan Castle. 

Shah-Abdol-Azim shrine, Rey. contains the tomb of: ‘Abdul ‘Adhīm ibn ‘Abdillāh al-Hasanī (aka. Shah Abdol Azim). Shah Abdol Azim was a fifth generation descendant of Hasan ibn ‘Alī and a companion of Muhammad al-Taqī. He was entombed here after his death in the 9th century. 

Toopkhaneh (Imam Khomeini Square; Tūpkhūneh; Cannon House). a major town square (Maidan-e Toopkhaneh) and a neighborhood in the south of the central district of Tehran. 

Ibn Babawayh Cemetery (Ibn-e Baabevey), Rey.

Grand Bazaar (Bâzâr Bozorg-e Tehrân), (South of Tehran. (''Metro: Panzdah-e-khordad''). The main entrance is on 15 Khordad Ave.). A historical market. The Grand Bazaar is located in southern Tehran; its many corridors are over 10 km in length. There are several entrances, some of which are locked and guarded at night free.

Milad Tower. Milad tower is the fourth tallest tower in the world and 12th tallest freestanding structure in the world, and it is visible from almost everywhere in Tehran. Note that tickets to enter the observation lounge must be reserved in advance. There is a rotating restaurant at 390m above the ground, which has become one of the most expensive restaurants in the country.  

Mausoleum of Ayatollah Khomeini, (Metro: Haram-e-Motahar, on the southern edge of the city). Free. 
Museums

Golestan Palace
Tehran has more than 50 museum and 100 art galleries.

Treasury of the National Jewels, (Ferdosi St, near the corner of Jomhuriyeh Eslami Ave; next to the Iranian Central Bank). Saturday to Tuesday from 2PM to 4:30PM. The largest collection of jewels found anywhere in the world. You'll get to see the collection of jewels including Darya-e-Noor diamond, the sister diamond to the Kuh-e-Noor diamond. Other highlights include the world's largest uncut ruby and a free standing golden globe made from 34 kilograms of gold and an astounding 51,366 precious stones. Admission: IRR150,000. Free tours (with paid admission) are given in English.

National Museum of Iran, 30 Tir Ave, Emam Khomeini Ave, [9]. Contains some of the most precious and significant artefacts from ancient Persia (dating back to 5000BC) and post-Islamic Persia (800AD). The must sees are the Salt Man, a prince who was naturally mummified in a salt mine for 2000 years. His clothes and jewels are still intact. Furthermore, there are statues of Parthian kings and there are many examples of Persian columns and structures. The building itself is a masterpiece from 1930s Iran.

Golestan Palace. the oldest of the historic monuments in Tehran. The Complex consists of 17 palaces, museums, and Halls. The Golestan (Rose Garden) citadel is one of mainly visited places in Tehran, which was the Qajars' royal residence, and its garden is an oasis of coolness and peace in the heart of the city. The major building, architecturally unpretentious, houses a museum with objects from the Qajar period in the self-important style of last century. In the Golestan garden, a one-story pavilion to the right and a short distance from the entrance, shelters one of the best organized museums in Tehran. It encloses about thirty showcases presenting almost everything related to Iran, which makes up the critical originality of Iranian life in the a variety of provinces of the country.

Niavaran Palace, is a historical complex which consists of several buildings and a museum. The Sahebqraniyeh Palace, from the time of Naser al-Din Shah of Qajar dynasty, is also located inside the complex. 

Abgineh Museum (Glassware Museum), (No.75, 30th of Tir Ave., Jomhuri Ave.), ☎ +982166708153, 982166708154, [12]. prehistoric Glass and Ceramics  

Sa'd Abad Gallery of Fine Arts

Carpet Museum & National Rug Gallery, exhibits a variety of Persian carpets from all over Iran, dating from 18th century to present. It has a library that contains 7,000 books. 

Reza Abbasi Museum, named after Reza Abbasi, one of the artists in the Safavid period. The collections of this museum belong to a period from the 2nd millennium BC to the early 20th century. 

Tehran Museum of Contemporary Art, Features the works of great artists such as Van Gogh, Pablo Picasso and Andy Warhol. The collection of these paintings were selected by the former Empress Farah Diba.  

Darabad Museum of Natural History. Iran's most famous museum for nature and wildlife  edit
Saadabad Palace, is a palace built by the Pahlavi dynasty of Iran in the Shemiran area of Tehran.The complex was first inhabited by Qajar monarchs and royal family in the 19th century.Currently, parts of the Saadabad Palace compound are museums, in which visitors can roam through and look at the rich history of Iran.

Time Museum, No. 12, Baqdadi St., Zaferanieh St., Vali Asr Ave., ☎ +98 21 241 7336/7. The 700 Sq. m building is situated in a 6000 Sq. m garden. It is embellished with various dazzling Iranian arts and crafts such as ornamental brickwork, arched ceiling decorated with painting, plasterwork, tile work, nodular wood work and stone work. The garden includes biological clocks, sundials, and geologic measures of time. The building includes mechanical clocks, watches, and calendars.

Money Museum, Mirdamad street. Coins and banknotes from different historic periods.

Bagh-e Ferdows (The Mohammadieh Palace), Tajrish, Shemiran, North Tehran, between Zafaraniyeh and Jafar Ābād. It is part of a palace complex consisting of two castles, the North Castle and the South Castle, of which the former has decayed. Since 2002, it houses Film Museum of Iran.  

Abū-Muhammad Muslih al-Dīn bin Abdallāh Shīrāzī, Saadi Shirazi (Persian: ابومحمد مصلح الدین بن عبدالله شیرازی‎), known by his pen-name Saʿdī (Persian: سعدی‎) or simply Saadi, was one of the major Persian poets and literary men of the medieval period. He is not only famous in Persian-speaking countries, but has been quoted in western sources as well. He is recognized for the quality of his writings and for the depth of his social and moral thoughts. Saadi is widely recognized as one of the greatest poets of the classical literary tradition. His best known works are Bustan (The Orchard) completed in 1257 and Gulistan (The Rose Garden) in 1258. Bostan is entirely in verse (epic metre). It consists of stories aptly illustrating the standard virtues recommended to Muslims (justice, liberality, modesty, contentment) and reflections on the behavior of dervishes and their ecstatic practices. Gulistan is mainly in prose and contains stories and personal anecdotes. The text is interspersed with a variety of short poems which contain aphorisms, advice, and humorous reflections, demonstrating Saadi's profound awareness of the absurdity of human existence. The fate of those who depend on the changeable moods of kings is contrasted with the freedom of the dervishes. Saadi distinguished between the spiritual and the practical or mundane aspects of life. In his Bustan, for example, spiritual Saadi uses the mundane world as a spring board to propel himself beyond the earthly realms. The images in Bustan are delicate in nature and soothing. In the Gulistan, on the other hand, mundane Saadi lowers the spiritual to touch the heart of his fellow wayfarers. Here the images are graphic and, thanks to Saadi's dexterity, remain concrete in the reader's mind. Realistically, too, there is a ring of truth in the division. The Sheikh preaching in the Khanqah experiences a totally different world than the merchant passing through a town. The unique thing about Saadi is that he embodies both the Sufi Sheikh and the travelling merchant. They are, as he himself puts it, two almond kernels in the same shell.