Until last week, when­ev­er I thought about Copen­hagen — and I admit that was not often — three peo­ple came to mind: Niels Bohr, Jan Gehl, and Sarah Lund.

Bohr’s Insti­tute for The­o­ret­i­cal Physic­s was at the cut­ting edge of the­o­ret­i­cal physics in the ear­ly 1930s, and the set­ting for a mem­o­rable per­for­mance of Goethe’s Faust by the sci­en­tists (much more on this here). Jan Gehl is an influ­en­tial Dan­ish urban­ist and archi­tect who pio­neered pedes­tri­an­iza­tion in cities. In 1962, Copen­hagen became the first city to pedes­tri­an­ize a main thor­ough­fare. The two-kilo­me­ter-long Strøget is Europe’s longest pedes­tri­an street or, to be more accu­rate, col­lec­tion of streets. And, of course, as all fans of crime fic­tion know, Copen­hagen pro­vides the set­ting for Detec­tive Inspec­tor Sarah Lund’s inves­ti­ga­tions in the superb Dan­ish TV series For­bry­delsen (The Killing, 2007).

But now when I think of Copen­hagen anoth­er name springs to mind, and with it a unique build­ing.

Last week I spent a relax­ing cou­ple of days in Copen­hagen. It’s a beau­ti­ful city of red-tiled rooftops, bicy­cles, cob­bled streets full of peo­ple rather than choked with cars, and colour­ful hous­es reflect­ed in canals. Great street per­form­ers too, like these two demon­strat­ing an impres­sive bal­anc­ing trick.

It’s also a city that is clear­ly seri­ous about its envi­ron­men­tal responsibilities: for instance, the city recy­cles more of its waste than any oth­er Euro­pean cap­i­tal. But above all it’s a won­der­ful­ly friend­ly city.

The man who did most to shape the city you see today is King Chris­t­ian IV who was known as the “archi­tect king”. Dur­ing his six­ty-year reign (1588–1648) he for­ti­fied the city and reclaimed land from the sea. He also built the Rosen­borg Palace (1606), with its moat and ele­gant red-brick tow­ers. One of its more unusu­al fea­tures is the Mir­ror Cab­i­net, cre­at­ed for Fred­erik IV in about 1700, a small cham­ber with mir­rors on each wall and even on the floor, which appar­ent­ly the King used to peer up wom­en’s skirts.

Beau­ti­ful though the Rosen­borg Palace undoubt­ed­ly is, I was more impressed by anoth­er of Chris­t­ian IV’s build­ings. The RundetÃ¥rn, or Round Tow­er, ris­es above the pedes­tri­an zone, on Købmagergade. Mod­elled on Tycho Bra­he’s famous obser­va­to­ry called Stjerneborg (the cas­tle of the stars), the 42-metre-high Round Tow­er is Europe’s old­est func­tion­ing astro­nom­i­cal obser­va­to­ry. Built between 1637 and 1642, it was part of Chris­t­ian IV’s Trini­tatis Com­plex which com­bined a church, a schol­ar­ly library (hold­ing some 10,000 books) and an obser­va­to­ry into one enlight­ened archi­tec­tur­al struc­ture.

But what is tru­ly remark­able about this tow­er — and appar­ent­ly it is unique in Euro­pean archi­tec­ture — is the 209-metre spi­ral ramp that leads up to the view­ing plat­form at the top: a sin­u­ous path­way, paved with ochre-coloured bricks, wind­ing itself sev­en and a half times around the hol­low core of the tower. It’s an extra­or­di­nary struc­ture that feels almost nat­ur­al rather than man-made, as if it is a stone tree that has grown out of the heart of the city. As I walked up the spi­ral path, I was remind­ed of the fan­tas­ti­cal tow­ers of Dutch artist MC Esch­er or some­thing dreamed up by Borges.

It’s said that when Tsar Peter the Great of Rus­sia vis­it­ed the city in 1716 he rode up to the top on horse­back. And in 1902, a vis­it­ing Ger­man demon­strat­ed the pow­er of the lat­est Benz-Gagge­nau auto­mo­bile by dri­ving up the spi­ral ramp. (There’s an amaz­ing pho­to of this sur­re­al moment in tech­no­log­i­cal and archi­tec­tur­al his­to­ry here.) For­tu­nate­ly, Copen­hagen has sub­se­quent­ly decid­ed to keep cars in the city firm­ly under con­trol. There is lit­tle doubt that if, like me, you pre­fer to explore a city on foot or on bicy­cle then this is as close as it gets to urban heav­en. More peo­ple cycle to work in Copen­hagen than in the entire Unit­ed States of Amer­i­ca, as Taras Grescoe has point­ed out.

From the top of the Round Tow­er you can gaze out across the roof­s­cape of the medieval city cen­tre, with its wind­ing streets and half-tim­bered hous­es. In the dis­tance you can even see the 8‑k­ilo­me­tre-long Øresund Bridge that links Den­mark and Swe­den.

Copen­hagen is a mem­o­rable city, designed for peo­ple rather than cars, and one that oth­er cities have much to learn from. It’s a com­mu­ni­ty with a rich his­to­ry, not a col­lec­tion of dense­ly pop­u­lat­ed, Bal­lar­dian traf­fic islands, as so many cities have become. For vis­i­tors from Britain, it’s not a cheap city though — eat­ing out was cer­tain­ly more expen­sive than Berlin, for instance. But we found some great cafés and restau­rants. A cou­ple that spring to mind: a real­ly excel­lent fish restau­rant is the Fiske­bar, near the cen­tral sta­tion; and if you like Ital­ian food, La Roc­ca is the place for you. And of course, wher­ev­er you go the many pas­tries and dif­fer­ent types of bread are all deli­cious. I wish we had a Dan­ish Kon­di­tori near us…

So thank you — or “Tak” as they say there — Copen­hagen for mak­ing me feel wel­come (at the air­port the bor­der guard actu­al­ly said “wel­come to Den­mark!” when he hand­ed me my pass­port; I bet UK offi­cials don’t say that at Heathrow). And thank you Copen­hagen for intro­duc­ing me to the RundetÃ¥rn and to your archi­tect king, Chris­t­ian IV.

As ever, you can find more pic­tures of Copen­hagen on my Flickr page.