Azadi Tower, built in 1971 to commemorate the 2500th anniversary of the first Persian empire, is one of Tehran's visual icons. Designed by Hossein Amanat, it ingeniously combines modern architecture with traditional Iranian influences, most notably the iwan-style of the arch, which is clad in 8000 pieces of white marble. It's worth going inside to see the complex structural engineering that forms the bones of the design and for the view from the gallery at the top.
You can reach the top by stairs or lift. At the base are galleries with changing exhibitions and a cafe.
To reach the tower, which sits in a large oval park, you'll need to tentatively negotiate the maelstrom of traffic that is an almost constant feature of the square.
Azadi Sq was the scene of much protest during the 1979 revolution and remains a focal point for demonstrations today, including some huge demonstrations during the post-election crisis in 2009.