In this project I developed two solutions for visualizing air velocity calculated from a CFD simulation on the Fortress of Mytilene. The first version of the project was published on the Euromed Conference in 2022 titled as “CFD Simulation and 3D Visualization on Cultural Heritage sites: The Castle of Mytilene”. This paper presents a CFD and 3D Visualization pipeline to simulate wind flow over a heritage site and then visualize the results. As case study, a coarse 3D geometry model of the Fortress of Mytilene, Lesvos island, Greece and its surrounding was generated from open access Digital Elevation Models. The CFD simulation of the air flow on the wider heritage site area was performed using the steady-state version of the in-house flow solver IBOFlow®(Immersed Boundary Octree Flow Solver) developed at Fraunhofer-Chalmers Research Centre. All the simulations were completed considering the mean wind direction and wind speed during the last 22 years from actual weather data retrieved from Open Weather Map. The visualization results were achieved through Unreal Engine, using built-in visualization tools and a tailored-made plugin to visualize the air flow over the monument and on the monument’s wall. As discussed in the conclusion section, the overall process proposed in this paper can be implemented for an initial assessment of the effect of environmental parameters over any heritage site and moreover, it may form the basis for valuable assistive tool for conservators and engineers.