Platforms were fitted on top of the crosstrees and they were known as the tops. Until the end of the 17th century their basic shape was  circular and it was not until the beginning of the 18th century that the rear edge began to be straightened out, and in the first half of the 18th century the rear edge became quite straight, and the sides equally so, only the front third remaining elliptical in outline.
   From the 13th to the 16th century the tops possessed fairly high guard rails, and were therefore often termed crow's nests. These rails were sometimes made of massive wooden boards, sometimes from a wooden latticework, and they were usually brightly painted. From the middle of the 16th century onward the rails of the tops grew steadily lower, until by the last quarter of the 17th century they consisted of only a narrow ring. Even the bright colours disappear, and from the middle of the 17th century the tops were uniformly black in colour .
  Until the middle of the 17th century tops were carried on all crosstrees,(lower mast, topmast, topgallant and bowsprit). Thereafter only the lower mast crosstrees and the sprit crosstrees were fitted with a top, and the latter also disappeared with the abolition of the sprit top mast around 1720.
  The construction of the tops remained fairly well unchanged throuh the centuries. The top decking was about 1,16 x the crosstree in size, and was assembled from two layers of planking (forward and aft athwartships, sides fore and aft). For the model maker this procedure is, of course, too complex. He should cut his top decking from a sheet of wood, and score the joints with a knife. The thickness of th top decking was about 3ins to 4ins. The lubber's hole was 0,4 x the width. The sprit top only had a small opening, just large enough for the bowsprit knee and the heel of the topmast.
The ring which surrounded the top was supported by a number of ribs, which were distributed radially at even spacings. The ribs were rectangular and had a thickness of 3ins to 4ins at the ends. The ribs, always even in numbers, were spaced 12 to 18ins apart at the edges of the top. The holes for the topmast shroud chain plates have to be drilled and filed out to a rectangle with radiused corners. On round tops the foremost hole is located slightly ahead of the forward edge of the lower mast, and the after hole midway between the forward hole and the middle of the after half of the top; in the case of angular tops it was about 8 to 12ins ahead of the after edge. The remaining holes were spaced out between them at regular intervals.