Making the world better, one answer at a time. The primary germ layers (endoderm, mesoderm, and ectoderm) are formed and organized in their proper locations during gastrulation. Endoderm, the most internal germ layer, forms the lining of the gut and other internal organs. Ectoderm, the most exterior germ layer, forms skin, brain, the nervous system, and other external tissues. Mesoderm, the the middle germ layer, forms muscle, the skeletal system, and the circulatory system.
Eiffel Tower. The Eiffel Tower, located in Champ de Mars in Paris, is a tall wrought-iron structure made by man. It is one of the most famous monuments of the world. It is the most famous landmark of Europe, held the record as the tallest man-made structure of the world from 1889 to 1930 with its height of 324 meters.
Perhaps the most recognizable structure in the world is the Eiffel Tower located Paris, France. It was specifically constructed as the entrance gate into the World Fair that took place in the city in 1889. This fair was hosted to celebrate the centenary celebration of the French Revolution. Looking at the massive iron structure, people always want to know how long did it take to build the Eiffel Tower. It took 2 years, 2 months and 5 days to build the tower, a feat that is truly remarkable considering that the builders did not have access to modern gadgets and tools that are present today. The tower is named after the builder and architect, who designed it.