Visa requirement for stays of 6 months but less than 90 days per EU country

Unfortunately, the regulation is not 90 days per country, it's 90 days for the entire Schengen zone (most of Europe). The basic rule is that, traveling on a US passport (that is, in the normal tourist mode, without a visa, you can only legally stay in the "Schengen zone" (25 countries) for a maximum of 90 days in the 180 days after first entry into any of the Schengen zone countries. Here's a link to prior discussions here: link to prior discussions of Schengen 90-day rule The 25 European countries included in the Schengen zone are: Italy, France, Germany, Austria, Belgium, Czech Republic, Denmark, Estonia, Finland, Greece, Hungary, Iceland, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovak Republic, Slovenia, Spain, Sweden, and (apparently since Dec 2008) Switzerland.

Yes and No. There is no EU visa requirement, the Immigration requirements are per country, with the notable exception of the Schengen Agreement (Google it or look it up in Wikipedia). The basic impact is that you only get 90 days total for nearly all of the EU. The exceptions are the UK and Ireland, plus non EU countries like Croatia, Turkey. So if you can limit yourself to 90 days in most of Europe, then spend the rest of the time in these other countries, then 6 months is doable.

As the others have said, you cannot stay in the Schengen zone for more than 90 days total within a 180 period. Any extra time would require a visa which is issued by each country. So to continue to travel around Europe, you'd need multiple visas. And the non-Schengen nations also have limits on how long you can stay without a visa. If you desire to travel for 6 months, you will need to do some extensive and careful planning.

Just to round out the subject. If you are really determined to stay in the Schengen Countries for more than 90 days, and up to the six months; then you can certainly go through the visa process. For this, you would typically apply to the country of your entry in the Schengen zone, or the country that you will spend the majority of your time. You will do the typical paperwork applications, then usually you must also provide things like proof of financial support (bank info or proof of income, like a pension); Medical coverage, and any number of other details about your purpose in being there. The idea is to get some assurance that you will not be trying to work while there, or be a medical burden. Under this visa, you can stay for six months pretty easily, and while the Visa may be issued by Germany for example, it gets you travel in any of the Schengen countries for the period, no need for multiple visas. For the other countries not covered by the Schengen zone, lengths of stay vary, but typically range from 90 days to 6 months for a US passport holder, with special visa requirements for Russia and a few of the other old Soviet countries.

Thanks to all of you who posted replies. Now I understand how the Schengen Ageement works but I haven't yet decided what to do. However, I liked the suggestions of Turkey, Croatia, UK, Ireland and Russia and will be looking into these possibilities rather than applying for the longer than 90 day visa as I understand that it could take longer than 8 weeks to get.