Transparent building appeals to imagination. The availability of glass in all shapes and sizes is continuously increasing; architects and engineers thankfully make use of the given opportunities. But glass has also some specific disadvantages, as it’s extreme brittleness. Luckily more materials are available that offer the desired transparency; transparent plastics might be a promising addition to the world of transparent building. The transparent plastics that are considered most suitable for building applications are Acrylic (PMMA) and polycarbonate (PC). In this research the behaviour of these transparent plastics is analysed and it is investigated whether and how the materials can be used in building structures, to further explore the dream of completely transparent buildings. Transparent plastics show some, for building materials, unusual characteristics, as thermoplastic and visco-elastic behaviour, special production techniques and a very low ratio between Young’s modulus and strength. This requires a different design approach. A case study is performed to get more feeling for the design with thermoplastics. To be able to use the freedom of shape and to explore the limits of the materials an observation tower is designed. An entirely transparent tower, made completely from transparent plastics. The design demonstrates that it is technically possible to design building structures in acrylic and polycarbonate. Transparent plastics offer promising possibilities for building design but still a lot will have to be investigated further before they can really be used for load bearing structures. For instance the development of standard details, the investigation of fire safety, the buckling behaviour of plastics and the long-term behaviour for a design life over 20 years, which is now the limit by a lack of data,. This will be a trajectory of years but other materials have come that long road before. Once the plastics industry recognises the opportunities of investing in this new product market the development of suitable building products, details and optimal material compositions will certainly progress faster. Transparent plastics will probably never become a threatening substitute for standard glazing applications, but they have the ability to become a worthy colleague to glass in the future and an interesting addition to the world of transparent building.