Citizens of most countries can obtain a visa on arrival. However, citizens of the UK, the US and Canada, as well a handful of other countries, must obtain a visa in advance. For those requiring a visa, you must either apply as part of an organised tour or have a sponsor in Iran. It is possible to arrange your own organised tour with a group of friends via a travel agency. If you only wish to visit Tehran and have connections in the country, it is easier to apply for a business visa. Although obtaining a tourist visa can sometimes be a long and arduous process, it is more than worth the hassle.