Biomonitoring of Pt, Pd, Pb, Mn, Cu, Fe and Zn was conducted using leaves (two and six months old) of laurel (Laurus nobilis L.) ornamental shrubs grown in 14 sampling sites located on the central green belts of six avenues and streets of Athens. In this biomonitoring, we determined, for the first time in Greece, the concentrations of the new urban “pollutants” Pt and Pd, and we estimated the correlations among the concentrations of all the above-mentioned metals as well as among the metal concentrations and the traffic load. Cluster analysis and principal component analysis (PCA) of the data revealed three distinct groups of metals and two groups of sites (one with high and the other with relatively low levels of pollution). Using varimax-rotated PCA for the metals, four factors were extracted explaining 92.3% of the total shared variance, which are further discussed. The importance of seasonal timing of sampling is revealed by the data and discussed in connection with the meteorological conditions.