Tehran has all the makings of a gigantic city - it's busy, traffic jams are a given and there are many diversions to occupy your time. For the background story on the city of Tehran, go to wikipedia, and for some genral tourism information, see Iran Tourism & Touring or the Iran Traveling Center. If you need official information, Tehran Municipality is your best bet.
If you are looking for different activities and ways to entertain yourself in Tehran, go to Tripadvisor to find out a vast number of possiblities to make the most of this trip. Look at Tehran 24 for pictures of contemporary life and daily landscapes.