Hydrangea macrophylla is from the Hydrangeaceae family. This type of Hydrangea is called a Hortensia Hydrangea, commonly known as mopheads. They are a deciduous shrub with wide ovate leaves and big balls of small fertile flowers but mainly sterile flowers. The colours vary depending on the acidity of the soil, ranging from blue - deep pink.

I have to admit I do not like the appearance of these plant, I think they especially look bad when the whole plant turns brown for a number of weeks as it dies in the winter. However, they do look beautiful close up with this pastel-like colouration.
(Click image to view in high quality) Taken by myself.