swamps or small ponds cover the highest terrace. These are mainly forested areas (pine forest). Climate Warsaw experiences an oceanic climate, denoted by Cfb by the Köppen climate classification. However, the city has clear humid continental influences (Köppen: Dfb), and the city is defined as such with old data, prior to the recent effect of climate change and the city's urban heat island. Meanwhile, by the genetic climate classification of Wincenty Okołowicz, it has a temperate "fusion" climate, with both maritime and continental features. The city has cold, sometimes snowy, cloudy winters, and warm, relatively sunny but frequently stormy summers. Spring and autumn can be unpredictable, highly prone to sudden weather changes; however, temperatures are usually mild, especially around May and September. The daily average temperature ranges between in January and in July and the mean year temperature is . Temperatures may reach in the summer, although the effects of hot weather are usually offset by relatively low dew points and large diurnal temperature differences. Warsaw is Europe's sixth driest major city (driest in Central Europe), with yearly rainfall averaging , the wettest month being July. Cityscape Urbanism and architecture Warsaw's long and eclectic history left a noticeable mark on its architecture and urban form. Unlike most Polish cities, Warsaw's cityscape is mostly contemporary – modern glass buildings are towering above older historical edifices which is a common feature of North American metropolises. Warsaw is among the European cities with the highest number of skyscrapers and is home to European Union's tallest building. Skyscrapers are mostly centered around the Śródmieście district, with many located in the commercial district of Wola. A concentric zone pattern emerged within the last decades; the majority of Warsaw's residents live outside the commercial city centre and commute by metro, bus or tram. Tenements and apartments in the central neighbourhoods are often reserved for commercial activity or temporary (tourist, student) accommodation. The nearest residential zones are predominantly located on the outskirts of the inner borough, in Ochota, Mokotów and Żoliborz or along the Vistula in Powiśle. A seat of Polish monarchs since the end of the 16th century, Warsaw remained a small city with only privately owned palaces, mansions, villas and several streets of townhouses. These displayed a richness of color and architectonic details. The finest German, Italian and Dutch architects were employed, among them Tylman van Gameren, Andreas Schlüter, Jakub Fontana and Enrico Marconi. The