We report on an evaluation of the stability of four different GNSS monuments that was conducted in the summer of 2010. The monuments were monitored by forward intersections using a survey system consisting of two robotic total stations and a set of retro reflecting prisms. The system was operated for almost 3 months, performing observations in two faces with a repetition cycle of 5 min. Movements in excess of 6 mm were detected. The results show clear evidence that the detected deformations are related to variations in temperature and solar radiation and can be suppressed by simple shielding of the monument. Furthermore, our project is a step towards the realization of continuous cartesian connections at geodetic fundamental stations. Keywords Geodetic monitoring, GNSS monuments, Local-tie monitoring, Fundamental geodetic stations, Global geodetic observing system (GGOS), Co-located space geodetic techniques, Continuous cartesian connections (CCC).