This a really beautiful Lego set that for me, being fairly new to building Lego was very challenging but lots of fun!! I did it over 2 days around 5 hours in total to complete. The bags are not numbered like other sets..... So be prepared for a little more searching of the pieces! The instruction manual is sleek and includes heaps of information about the United Nations Headquarters history and architects, including the designer of this Lego set too. Something a little bit extra and special compared to other sets. Definitely keen to do more of the Architecture series now.