Athens, as many other metropolitan areas, is experiencing a severe summer heat island. We will present measurements of urban canyon heat islands in Athens and discuss the effects on building energy use, urban environment, and air quality. Appropriate heat-island mitigation technologies include use of cool materials for urban surfaces (roofs and pavements) and shade trees. Advances in development of cool roofing and paving materials including traditional cool surfaces (white and light-colored materials), near-infrared cool colored materials, and experimental highly reflecting thermochromic coatings will be discussed. Finally, we will discuss the European Cool Roof Rating Council being initiated in association with the Heat Island Group at LBNL.