I think it would be any Christmas market in December in Tallin. I like very much the Old town: you should know that its divided into old cities, the Upper town (Toompea, wher the castle is) and the Lower town (its centre is Raekoja Plats, Town Hall Square). Outside Tallin you can visit the Open Air Museum, with old wooden building from all Estonia.

I thing the medieval town special the wall is the biggest in Europe. And I thinh to get a ship to Helsink is good idea.

If you love the medieval feel, you have to visit Olde Hansa restaurant in Old Town. I love everything about that restaurant. A bit pricey but worth it :)

Different options for different travelers. Before you visit you can get some help from http://www.visitestonia.com/en/ .

Go to Tartu! It is a university city, has many great eateries and a cool skeleton of a cathedral. You could also go to Narva, climb the castle and look into Ivangorod, Russia... it is a Russian speaking city, so it has quite a different feel from other parts of Estonia. You could also go to Vôru, which is more of a folkloric capital of Southern Estonia.

I have spend so many days in estonia that i can not caunt them and i wwoud definetly tell to you to skip tallin and go directly to tartu. when you get there you will understand it. Tartu is also THE party city

Tallinn is nice, especially the old town, you got some good tips here already. Other than that, take the 4 hour ferry to Suomi (Helsinki)and spend the day - cool experience!

All of the old town is beautiful, but do go down the side streets, such as Lai, Uus, Aia. There used to be a great little buffet/cake shop on the corner opposite Puhavaimu church (and the church is definitely a must as well), and there is the much more famous Maiasmokk at the top end of Pikk. If you go out of the town centre a little you can probably still see some of the old wooden houses that are sadly rapidly disappearing. The streets near Kadriorg used to be good for this.

We were able to easily walk the old part of the city in a day. It is beautiful! There are various bus tours available, but the availability may change in the winter months. There seemed to be a number of ferries - if you like to travel to other cities this way.

We had a couple of days in Tallinn in August. I found this website http://www.estadventures.ee/ Did the brew with a View tour. Learned lots of stuff that we wouldn't have by just walking around and went to a couple of great bars we wouldn't have found by ourselves

I will be traveling there next summer I would love to read any answers you may get. I have been reading Frommer's Scandinavia and it has some good advice and tourist info in that book.