There are several iconic LEGO sets that include over one thousand small pieces and prove extremely difficult to assemble. Everyone has their own opinion on which is the most difficult, but there is not one right answer. LEGO has shared their biggest LEGO sets, crowning the LEGO Art World Map of the biggest. However, LEGO-based outlets have determined many sets as the most difficult, including the Titanic, Millennium Falcon, roller coaster, Taj Mahal, and more. Try out some of the most iconic sets for yourself and find the most difficult one for you.