Hessdalen is a small valley in the central part of Norway. At the end of 1981 through 1984, residents of the Valley became concerned and alarmed about strange, unexplained lights that appeared at many locations throughout the Valley. Hundreds of lights were observed. At the peak of activity there were about 20 reports a week.Project Hessdalen was established in the summer of 1983 to study Unidentified Aerial Phenomenon (UAP) and Unidentified Flying Object(UFO) sightings. A field investigation was carried out between 21 January and 26 February 1984.Fifty-three light observations were made during the field investigation. Assistant professor Erling Strand, the founder of the Hessdalen project, conducted together with the author the first international congress of the Hessdalen phenomena in 1994. This congress attracted scientists from all over the world and boosted the scientific research in Hessdalen.Statements from the congress indicated that explanation of the phenomena could lead to new concepts in physics. This congress also started the collaboration between stfold University College in Norway and CNR in Italy. Together with Dr. Stelio Montebugnoli the author started the EMBLA project, with the purpose of studying the electromagnetic radiation and behavior of the Hessdalen phenomena in 1999.Lights are still being observed in the Hessdalen Valley, but their frequency has decreased to about 20 observations a year.The following is the conclusions from over 25 years of research and after Italian SETI scientists got involved with much more highly sophisticated equipment.