The adoption of 5G has recently picked up pace and across the globe commercial deployments are more and more numerous. In addition to better performance, 5G brings, among others, management and operation flexibility, thus allowing industry verticals to exploit features of the telecommunication networks that go far beyond the new mobile access capabilities. As with any new technology, the integration, testing and validation of new vertical applications pose great challenges at both management and operational levels. In this context, there is an evident need for 5G infrastructure facilities that offer testing and validation capabilities through a flexible experimentation framework. This paper presents the 5GENESIS EU-funded research project Experimentation Facility and the results of the validation campaigns conducted in its five experimentation platforms. The tests and obtained results were facilitated by the 5GENESIS Suite, an open-source framework providing test automation and result analytics.