Six days in Helsinki and Tallinn: Two Capitals, One Sea, Opposite Histories

Start at the sea end of Esplanadi and walk inland. The park is a strip of lawn and lime trees between two boulevards running up from the harbour, and in summer it is where the city sits down: office workers on the grass, a free concert most evenings on the stage at the water end, and gulls that have worked out what an ice cream is.

The Old Market Hall is the low red brick building on the quay, open since 1889 and the best eating on the waterfront. It is one aisle of stalls doing smoked fish, reindeer, cheese and bread, with counters to sit at. The famous oddity is the stall selling beaver sausage; the sensible order is salmon soup. Outside on the cobbles, the open air stalls sell berries and produce all year, and in high summer the thing to buy is a bag of sweet green peas that you pod and eat raw as you walk.

Then climb Senate Square in the evening light. Engel's cathedral stands white and green domed at the top of a very wide flight of steps, with the twelve apostles along the roofline. It was finished in 1852 and it is better from outside than in, which is convenient, because there is now a charge to go in and the interior is austere even by Lutheran standards. The three sides below it, the university, the government palace and the merchant's house, were built to make a town of a few thousand people look like the seat of a grand duchy, and they succeed so well that Cold War film crews shot St Petersburg here.

Uspenski Cathedral is ten minutes from the market square, up a rock on the Katajanokka side of the harbour, and you will have seen its red brick and five gold domes from every waterfront view already. It serves Finland's Orthodox minority, a leftover of the Russian century, and after the whitewashed restraint of the Lutheran cathedral the dark icon heavy interior is a shock. Twenty minutes, and it is closed on Mondays.

Then take the boat out from the market square quay. Suomenlinna is a fortress across six linked islands about twenty minutes out, and the boat runs on an ordinary HSL ticket, the same one that works on the trams. Sweden began building it in the 1740s at enormous expense to hold its eastern flank and called it the Gibraltar of the North, then lost it in 1808 without much of a fight: the Russians besieged it, no relief came, and the commander Carl Olof Cronstedt surrendered after two months. Finland was ceded shortly afterwards, Cronstedt was condemned as a traitor by a king who was himself deposed soon after, and he spent the rest of his life gardening.

What makes it worth the whole day is that eight hundred people live out there. There is a school and a shop, and the ramparts, dry docks, tunnels and grass banks are simply their landscape. Follow the blue signposted route across the bridges to the King's Gate at the far end, then come back along the southern shore where the cannons face the sea and people swim off the rocks in July. The Ehrensvärd Museum in the commandant's house explains the rest: it belonged to Augustin Ehrensvärd, who built the place and is buried in the courtyard outside.

Temppeliaukio was quarried straight down into a granite outcrop in a residential block of Töölö and finished in 1969. From the street you see almost nothing, just a low copper dome sitting in the rock. Inside, the walls are blasted rock face left rough, and the dome above is twenty two kilometres of copper strip wound in a spiral. It is one room, it takes fifteen minutes, and the acoustics are good enough that hearing a concert in it is a completely different experience from filing through. Go at opening; the coaches arrive mid morning and the space is small.

Then walk back down to Oodi, the central library, which Helsinki built in 2018 facing the parliament across the road and meant every bit of the implication. The ground floor is a café and a hall, the middle floor has 3D printers, sewing machines, recording studios and kitchens anyone can book, and the top floor is a single white curve of reading room under a wooden hull with a terrace looking straight at the government quarter. It costs nothing.

Finish at the Yrjönkatu swimming hall. It is an art deco bath house from between the wars with a pool under a barrel vault and three saunas, and it runs single sex days: men on Tuesday, Thursday and Saturday, women on Monday, Wednesday, Friday and Sunday. Costumes are permitted and almost nobody wears one. The upper floor, afternoons only, adds a steam room, a wood heated sauna and a café where people sit in towels between rounds. This is not a spa and treating it as an ordinary public bath is the whole etiquette.

Take a morning boat. Tram 7 or 6T runs to the West Terminal door, check in closes well before departure, and the crossing takes about two hours through the archipelago and then open water. Go up on deck as you leave: Suomenlinna passes close on the port side and you get the fortress from the sea, which is how it was designed to be seen.

The boat berths at the Old City Harbour and the old town is fifteen minutes' walk, visible from the quay. Come in through Viru Gate, two round towers with conical roofs and a flower market underneath, all that survives of the fourteenth century east gate. Behind it is the lower town, where the merchants and artisans lived, as distinct from the hill where the bishop and the nobility looked down on them.

Town Hall Square opens out five minutes in. The Gothic town hall on its south side was finished in 1404 and has no surviving equivalent anywhere in northern Europe, with an arcade at ground level and a weathervane of a medieval guard on the spire that the city uses as a mascot. This was the marketplace and the place of executions, and the cafés round it are priced for cruise passengers.

Finish at Niguliste, St Nicholas's church, at the other end of the lower town. It was the German merchants' parish church, gutted by Soviet bombing in March 1944 and burnt again in the 1980s, and rebuilt as a museum rather than a working church. What is inside is why you go: Bernt Notke's Dance of Death, painted in Lübeck in the late fifteenth century, in which a pope, an emperor, a cardinal and a king are led away by skeletons. Only the first seven and a half metres survive.

Toompea is the limestone hill the whole town grew under, reached by two lanes called the Long Leg and the Short Leg, which were gated against each other because the hill and the town were separate jurisdictions. Alexander Nevsky Cathedral is the first thing at the top, built between 1894 and 1900 during the Russification years and placed opposite the seat of government on the highest ground in the city, which was not subtle. Independent Estonia debated demolishing it in 1928 as a monument to oppression and lost the argument. It survived the Soviet period too.

Across the square is the Toomkirik, older by six and a half centuries and much quieter. Founded in 1229, Catholic and then Lutheran from 1561, it is the burial church of the Baltic German nobility and the walls are hung floor to ceiling with the carved wooden arms of families who ran this country for seven hundred years and left in 1939. Climb the tower. Behind it, the Kohtuotsa and Patkuli platforms give you the roofscape everybody photographs, and both are free.

Come down in the afternoon to Vabamu at the foot of the hill. It covers 1940 to 1991: the Soviet occupation, the German occupation, the deportations to Siberia, the deportations again, and the singing that eventually ended it, told largely through recorded testimony from the people it happened to. Standing there, a day after leaving Helsinki, it is worth remembering that during those decades people in this city watched Finnish television to see what was on the other side of the two hours of water you have just crossed.

Walk north out of the walls. Kalamaja is the oldest suburb of the city, fourteenth century in origin, named for the fish houses that stood there, and it was a workers' district of one and two storey wooden apartment buildings mostly thrown up around 1900 for factory hands. Nobody with money lived there for a century, which is why it survived intact, and it is now the part of Tallinn to walk with no destination in mind: painted timber facades, small front gardens, a linear park where the railway used to run, and the Telliskivi complex of old rail workshops holding bars, studios, a flea market and the restaurants the city actually eats in.

Lennart Meri airport is four kilometres away and tram 4 runs to the terminal door in about fifteen minutes, so a late morning here costs you nothing.