This dataset contains concentration and velocity mesurements performed in the aerodynamic wind tunnel of the Ecole Centrale de Lyon. An idealized urban district was simulated by an array of blocks, and two rows of model trees were arranged inside a street. Reduced scale trees were chosen to mimic a realistic shape and aerodynamic behaviour. Three different spacings between the trees were considered: "zero" (no trees), "half" (9.5 cm distance between the crowns) and "full" (2.5 cm distance between the crowns). Different orientations (alpha) of the street with respect to the approaching wind were simulated. The aspect ratio of the street is reported as the height to width ratio of the street canyon H/W (e.g. HW05 means and aspect ratio H/W=0.5). The concentration measurements were performed with a Flame Ionisation Detector, while velocity measurements were perfromerd with a Hot Wire Anemometer and a Laser Doppler Anemometer. The measured data are described and discussed in the papers that can be found in the directory "biblio". The dataset contains both the raw data collected during the experiment and the organized data that are normalized and re-arranged in easy-to-read txt files. Brief description of the contents of the directories: boundary_layer: velocity measurements of the boundary layer above building roof. The data are presented in Fellini et al. 2022. drag_coefficient_trees: measurements of drag force and velocity performed in a small closed-circuit wind tunnel to determine the drag coefficient of the model trees used in the experiments. The data are presented in Fellini et al. 2022. alpha90: concentration and velocity measurements performed in a street canyon oriented perpendicularly with respect to the wind direction. The concentration data are presented in Fellini et al. 2022 for 3 different geometries of the streets (see Section 5 of the paper). The velocity data are presented in the draft Del Ponte et al. 2023. alpha60: preliminary concentration measurements performed in a street canyon with intersections oriented with a 60° angle with respect to the wind direction. For further details read the readme.txt files and refer to the papers in the "biblio" folder.