This paper investigates the design of airspace blocks using Voronoi diagrams and simulated annealing. This approach aims to optimize the layout of airspace blocks by minimizing the complexity gap between them. The algorithm is tested with different complexity metrics. By using Voronoi diagrams, which partition the airspace into regions around specified points, and simulated annealing, which iteratively refines solutions to find near-optimal configurations, the algorithm provides a systematic method for airspace design. The study focuses specifically on the French airspace, providing a real-world application of the proposed methodology. Through experimentation and evaluation, the algorithm demonstrates its ability to generate airspace block configurations that balance complexity. This research contributes to ongoing efforts in airspace management and optimization by providing insights and techniques for designing airspace structures that meet the evolving needs of air traffic control systems.