Prior to going there I can't say I've ever thought much about Tallinn. Having been there I now know, not only how to correctly spell its name, but what a fascinating place it is - in particular the Old Town which is one of the best preserved medieval cities in Europe. The Old Town, or Vanalinn in Estonian, possesses a neat symmetry in its circumference. You can enter Vanalinn at one medieval set of gates (Viru Gates) and follow various narrow winding cobblestone roads, past the central Raekoja Plats (Town Hall Square) and eventually come through to the end (northern) point of Vanalinn (Fat Margaret's Tower). Conversely you can start at the north end, at the Fat Margaret gate, and do it in reverse (a practical option if you are, like I was, staying in the Pohja/Sadama part of town). Much of the original old city wall has been retained and you can follow the wall as it jags round the parameter of Vanalinn.
The Wall on the western side separates Vanalinn from Toompea (Katedraal Hill) which sits on a high bluff around 30 metres above the Old Town. On the eastern side of the wall, especially in Müürivahe, the environs can get a bit smelly, it was decidedly "on the nose" when I visited, so much so that it put me off going to a restaurant I had singled out in this street! The wall towers and old merchant houses in the Lower Town with their reddish-orange roofs exude a real old world charm and you quickly come to appreciate the many different foreign influences that have exerted themselves on the city at different points in its history - Danish, Swedish, German and Russian (particularly this last one). You also get a feel for Tallinn's past of being once part of the Hanseatic regional trading confederation.
In the course of your peregrinations around the town you will see several notable old spiralled churches, especially around Pikk tänav or Harju tänav. Most visitors are happy to leisurely stroll through the cobbled streets and lanes (the Old Town is very navigable by foot in good shoes), but there is also a lot of transport that can be called on. You can take one of the myriad of bicycles fitted with a box for sitting in (velotaksos) operated by boys and girls who look like (and probably are) university students. A second option is you can tour the Old Town in a toy 'train', the Vana Toomas. Or you might like to hail down one of the horse-drawn carriages and be driven around by two rather severe looking lady drivers in smart if a little undertaker-like outfits.
Raekoja plats is the tourist centre of Vanalinn. It's a terrific spot to stroll round and take in the splendid architecture of the historic town. Great place also for lunch or dinner, Town Hall Square has many food choices, Estonian and Russian are popular naturally enough but also plenty of Asian, Italian, etc), as well as cafés and bars. In the Square you'll find a big selection of what Americans call 'sidewalk' eateries and cafés, all grouped in an L-shaped row, a very popular spot to dine in summer. Totally predictably there's a very touristy feel to the quarter and many restorans like Olde Hansa have gone over-the-top with the full medieval peasant kit for their serving staff! I spoke to one such ridiculously-attired waiter at this open air restaurant and I swear he sounded just like the dude in the Husqvarna TV commercial doing the exaggerated and deliberately silly Swedish accent!
During the day suvenyras stalls monopolise Raekoja Square with stacks of clothing, bags, amber, being flogged to the mingling multitude of visitors. This is one of the best places in Tallinn to score the cheaper-priced souvenirs. When the weather obliges there is often a band or musical performers of some description performing on the stage in front of the Town Hall ... that's when it gets really crowded in the Square! Hang around the edge of Raekoja long enough and you'll probably catch a glimpse of the horse-coach with the equestrian-garbed women drivers passing by or lined up for a fare.
Wandering around the Old Town especially close to Toompea Hill you will regularly run into sections of the still significantly intact medieval town wall. Tallinn owes its status as a UNESCO World Heritage city in no small measure to its winding, elongated and largely preserved historic old town wall. For the visitor, Vanalinn's numerous passageways and towers, most famously Kiek in de Kök and Tall Herman's Tower, are redolent of history. A particularly popular spot on the wall is Neitsitorn, which doesn't translate as "No-sit-on" but means Maiden's Tower (a somewhat ironic name given that at one time the Tower was uncomfortably close to a prostitutes' prison!). Neitsitorn, now a museum cafe, draws many visitors to sit on its long balcony high up on the wall and enjoy its fine views over the city. Kiek in de Kök with the voyeuristic connotations of its name (translating as "peeping into kitchens") is also now a military museum of sorts, appropriately enough as the tower still has nine cannonballs embedded in it from the 16th century Livonian War.
Walking east from Raekoja Plats, along Harju street towards Kesklinn (the New Town), you will reach Freedom Square, a plaza of great national significance to Estonians. Towering over the square is a huge cross which symbolises the Estonian people's struggle for independence after WWI, but more recently it was the gathering point for Estonians to proclaim their freedom from Soviet rule in 1991. Meetings and concerts are occasionally held here, but every time we visited, the predominant (indeed only) activity going on in the square was games of basketball between Tallinnese youth (basketball is Estonian's national sport appropriately for a nation of tall people) ... come to think of it, Tallinnese (linguistic purists humour me on this one!) is almost a homonym for 'Tallness'! The large and St Johns Cathedral, a focal point of the community, is at one end of the square. This broad, open space is well worth a look even if just to get away from all the souvenir shops, narrow alleyways and confined spaces of the Old Town for a bit.
Spending time in Freedom Square will afford you a respite from the Old Town's crowds and shops. Another, more aesthetically appealing place is the peaceful and tranquil parks on the western side of the city (between Toompea/Vanalinn and the central Baltic train station). Two in particular stand out, Schnelli Park and Tornide valjak. These long, delightful parklands represent a distinctive green zone cut off from the more densely populated parts of the inner city. Schnelli Park has a pond (Schnelli Tiik), once part of the medieval city's moat, a rockery and fountain at the southern end. Within the northern section, Tornide valjak, there is two (new) small quirky, themed gardens each celebrating a (sister city) connection with Tallinn - a Kiev (Ukraine) 'Ocean' garden with colourfully painted tin and plastic figures of fish and other pelagic creatures; and a Ghent (Belgium) garden with vivid silhouettes of children at play. In winter Schnelli Park and the other adjoining parks take on a whole different complexion, becoming fields of snow!