Is there any free and open Source FHIR Server?

Hi,
We want to use an FHIR server at our Medical University, for data protection we have to install the server locally, therefore we need a free and open source server.
What is the best one? Could you please help me?

The HL7 wiki has some options to choose from. See http://wiki.hl7.org/index.php?title=Open_Source_FHIR_implementations

Thank you so much. It is very helpful.

Since this post helpfully came up in a search for me, I am posting an updated link: Open Source Implementations - FHIR - Confluence