If you intend to transit through or visit several Schengen states (Germany, Austria, Belgium, France, Greece, Italy, Luxembourg, Netherlands, Portugal, Sweden, Spain, Denmark, Finland, Iceland and Norway) for up to 90 days for tourist or business purposes you have to obtain your Schengen visa from the Consulate of the country of your main destination. If your main destination cannot be ascertained, the country you first enter is responsible for granting your visa.Schengen visas for stays over 90 days are not available.
It must be noted that the border authorities are entitled to examine whether, at the time of entry, the prerequisites for entry continue to apply. This is international practice. If the prerequisites for entry or transit no longer apply, or if you are unable to provide the relevant evidence, you may be refused entry by the border authorities although you posses a valid visa. It is recommended that you carry with you the original letter / sponsorship declaration / copies of documents (e.g. proof of finance) which you enclosed with your visa application. This will help make the border control procedure easier and avoid delays at the border.