Platform nests are typically very large and get bigger every year as new material is added to freshen up the nest for the new breeding season.  They can be build on the ground, on high ledges, in trees, on telephone poles or on man-made platforms provided for some species subject to concern.
  

Ospreys usually nest in trees or on  man-made platforms not far from water.  Nests are often reused for many years and get to be very large.  A variety of different materials are used to make or re-surface the nests which are large enough to accommodate usually 3 growing birds and fairly large fish (up to four pounds or so) which are provided for them to eat.