Iran is among the old civilizations in the world and for this reason and due to its variety of climates and a number of beautiful natural attractions , it is considered as one of the worlds most important tourism centres . Of the worlds places recognized and registered as "the worlds Civilization Heritage" by UNESCO , four are located in Iran :

Takht-e-Soleyman ( ancient area including Atashkadeh Azargoshastb in the sasanids era) in Tekab, west Azarbayejan.
Takht-e-Jamshid ( ruins of the former capital of Iran in 2500 years ago) near the city of Shiraz.  
Naqsh-e-Jahan square ( a set of religious and public monuments from safavids era) near the city of Esfahan.  
Choghazanbil temple ( Aeelams imperial city in 3000 years ago) in Haftappeh 

Of the most important and famouse historical and attractive places in Iran :
 
Imam Reza (Shiit Enghth Imam) Shrine in Mashhad. 
Masjid-e-Shaikh Lotfollah (one of the Islamic architecture masterpieces in Safavids era) in Esfahan .  

Vank Cathedral (one of the most beautiful Iranian churches) in Esfahan . 
Atashkadeh Yazd (the largest and oldest Zoroasterians firetemple) in Yazd .
Arg-e-Bam (the worlds largest adobe building) in Bam . 
Maabad-e-Anahita (the stone temple of Ashkanian era) in Kermanshah . 
Qaleh-e-Falak -ol-Aflak (a large military castle in Sasanids era) in Khorramabad . 
Taq Bostan (of stone buildings in the Sasanids era) in Kermanshah . 
Pasargad (Cyrus's grave , the founder of Achaemenid dynasty in Iran) near Shiraz .  
Naqsh-e-Rostam (the largest stone building in Sasanids era) near Shiraz .  
Gounbad-e-Soltaniyeh (the world's highest dome) in Khodabandeh , Zanjan . 
Syoseh Pol(of the architecture masterpieces and in Safavids era) Pol-e-Khajoo in Esfahan . 
Banaye Shamsolemareh (Imperial Palace of Qajar kings) in Tehran . 
Tochal Telecabin (the world's longest telecabin installation) in Tehran .  
Ferdusi's Mausoleum - Tus.  
Attar's Mausoleum in Neyshabur .  
Hafez's Mausoleum (Hafeziyeh) in Shiraz.
 Saadi's Mausoleum (Saaeediyeh) in Shiraz .  
Qabus-ebne- Voshmgir Mausoleum (the world's highest brick tower) in Gondad-e-Kavus.  
Khayam Mausoleum in Neyshabur.  
Ibn-e-Sina Mausoleum in Hamadan. 
Bagh-e-Naderi in Mashhad.  
Karimkhan-e-Zand Mausoleum in Shiraz . 
Baba Taher Mausoleum in Hamadan.  
Arghe Bam in Bam.   
Pasarghad in Marvdashet. 

 In addition , other attractive places in Iran include Bazaar-e-Tehran , Bagh-e-fin-e-Kashan, Borj-e-Toghrol in Shahr-e-Rey, Bagh-e-Eram in Shiraz, Bagh-e-Shazdeh in Mahan, Masjid-e-Vakil in Shiraz , Masjid Aqa bozorg in Kashan , Masjid-e-Goharshad in Mashhad, Arg-e-Karimkhan in Shiraz, Darvaz-e-Qoran in Shiraz, Kakh-e-Golestan in Tehran , Masjid-e-Amirchakhmagh in Yazd, Masjid-Imam Khomeini in Esfahan, etc .
The most important natural places in Iran :
 
Damavand Peak in north-east of Tehran  
Ghar-e-Ali Sadr in Hamadan (cave)  
Crown imperial plains (fritillaria imperialis) at the foot of peak Dena  
Golestan forest in Bojnurd 
Kavir-e-Lut (desert) in the centre of Iran  
Lake Ourumiyeh in Azarbayejan  
Anzali marsh in Anzali port  
Lar Plain in the Mountain Damavand skirts 

There are many museums , exhibiting the world's and Iranian civilization , culture as well as history , the most important of which are as follows :

Ancient Iran museum in Tehran
 
Glassware and earthware museum in Tehran  
Natural history museum in Tehran  
Chehelsoton Museum in Esfahan 
Ganj Ali Khan bathroom museum in Kerman 
 Carpet Museum in Tehran 
Complex of Saadabad museums in Tehran  
Anthropology museum in Tehran  
Fine arts in Tehran  
Post museum in Tehran  
National Jewellery Museum in Tehran  
Modern Art Meuseum in Tehran 
Azadi cultural complex in Tehran