Beginning in 1997, Central Europe, between the Baltic and Adriatic Seas, has been covered by an unprecedented network of seismic refraction experiments (Fig.1A). These experiments - POLONAISE'97, CELEBRATION 2000, ALP 2002, and SUDETES 2003 - have only been possible due to a massive international cooperative effort. International Consortium consisted of more than 30 institutions from 16 countries in Europe and North America - Austria, Belarus, Canada, Croatia, Czech Republic, Denmark, Finland, Germany, Hungary, Lithuania, Poland, Russia, Slovakia, Slovenia, Turkey, and the United States. The majority of the recording instruments was provided by the IRIS/PASCAL Instrument Center and the University of Texas at El Paso (USA), the Geological Survey of Canada, and other countries. For example, in the CELEBRATION experiment, the total number was 1230 stations and 147 shotpoints located along seismic lines of a total length of about 9000 km. A large number of seismic sources and stations in all experiments means that besides 2-D approach along profiles, also 3-D approach could be implemented in data interpretation. Total length of seismic profiles in all experiments is about 20,000 km.