The purpose of the Eiffel Tower was to be an observation tower and mainly a tourist site. It was built for the fair in Paris in 1889 by Alexandre Gustave Eiffel. The tower was supposed to be built only for this purpose, but then the government of France decided to keep the Eiffel Tower where it was.
The Eiffel Tower was originally built as an entrance arch for the 1889 World's Fair in Paris. It was also part of a contest that it be easily taken apart & was supposed to stand for 20 years. It turned into a commercial asset & they decided to keep in up as an observation tower/ tourist attraction