As a consequence of their unique positioning and 3,5:1 plan ratio, the proposed twin 103m buildings of the latest expansion of the European Court of Justice (Luxembourg) led to the commissioning of a comprehensive set of wind-tunnel tests. Experimental testing and numerical analyses showed the buildings to be susceptible to unacceptably large wind-induced accelerations at the top levels. To mitigate these vibrations, a Tuned Liquid Damper (TLD) array is proposed and designed for both buildings. With an optimal design of the TLD array, total maximum reductions in top-level accelerations are found to be in the range of 35-40%, bringing tower accelerations below acceptable limits for human comfort. Experimental verification of the performance of the dampers is undertaken through 1:2 scale shaking table tests.