In this project, we took on the task of localizing an automatic vehicle and building a map of the car park in real time. This takes place within the car park of INRIA Rhone- Alpes on the CyCab vehicle with a Sick laser range scanner. Our method uses only laser scanners to retrieve the position and orientations of vehicles in the car park. With the detected vehicles as landmarks, CyCab performs a localization of itself and builds a map of the car park at the same time. Classical clustering and segmentation techniques to extract line segments from the laser scan data is applied. The key contribution of the paper is the extraction of vehicle poses from the line segments using bayesian programming. The method of FastSLAM is used in localizing CyCab and estimating the pose of vehicles in the car park. A set of hypotheses is obtained as a result. The second contribution is a method of combining the set of hypotheses together to form a final map of the car park.