Nobody else seems to have noticed the surprising lack of handrails seven storeys from the ground.
On the roof of a courthouse, this tour seems soft on laws of safety, as well as gravity. Although we are hard-hatted, harnessed and attached by a cable, it still feels precarious at times. Our guide, Lotta, assures us there is only one section where we could actually fall and "dangle over the edge".
Fortunately, she mentions this after we have made it.
"When I trained for this job, the first time I did that part, I cried," she says.
"I thought, what have I done?"
The rest of the track, atop Stockholm's former Parliament House, is better protected, but includes stairs and ladders, which we almost crawl up. Similar to the Sydney Harbour BridgeClimb, participants must kick along the gadget connecting their cable to the rail, while holding the other end, so taking photos is a one-handed, one-footed balancing act.
Every few metres, we stop to absorb spellbinding views of harbourside Stockholm. A flawless blue sky pierced by mediaeval towers frames a waterfront of multi-coloured houses. Meanwhile, our cheerier guide, Gabriela, tells stories of sex, religion and politics, which may not be dinner-party appropriate, but distract and educate the small group.
The old town's highest point is marked by the copper spire of the Tyska Kyrkan (German Church, or St Gertrude's), a baroque and Gothic structure that provides an impressive reminder of the German influence on Stockholm.
In the Middle Ages, Germans made up half the population and the majority of the city's politicians and merchants. This history is still reflected in street and place names, such as Tyska Brunnsplan (German Well Square) and Tyska Brinken (German Slope).
Gabriela's favourite stories, however, involve the recent scandals of the Swedish royal family. She grins proudly when speaking of Crown Princess Victoria, the heir to the throne, who controversially married her personal trainer in 2010.
"Her father, Carl XVI Gustaf, had little choice but to approve it," Gabriela says, "because he did not marry royalty either, discontinuing the established norms."
If the monarch had married Silvia Sommerlath, the half-Brazilian educational host he met at the 1972 Olympic Games in Munich, during the reign of his grandfather King Gustaf VI Adolf, he would have lost his position as heir apparent to the Swedish throne. Now 67, the king has also endured many headlines about rumoured affairs, as well as lurid tales from his bachelor days.
For a moment, we forget we are here to see Stockholm's skyline from on high. Our guides continue with information about the main attractions - the City Hall, the Djurgarden cultural complex, and the excellent Vasa Museum, home to one of the world's most complete and best-preserved shipwrecks. Afterwards, they take us on a stroll around the old town, pointing out architectural highlights and the best cafes to visit later.
The only one of its kind in Europe, the Upplev Mer (Experience More) rooftop tour has become so popular that large groups book it out most weekday mornings. I come on a shore excursion organised through Holland America Line, on a Baltic cruise, joined by a dozen passengers from the Eurodam. Independent travellers can pre-purchase (online) afternoon sessions or weekends.
The 75-minute tour is taken at a very slow pace, so it is less adrenaline pumping than expected, but the 43-metre height certainly provides a more thrilling alternative to the average walking tour. The fastest circuit was completed in three minutes by the company's snow shoveller, no doubt rushing his job on a cold winter's day. But I'm happy we hit the roof gently, in splendid Swedish sunshine, and made it safely back on land, before sailing away.
The writer was a guest of Holland America Line.
Eurodam's 12-day Baltic Gems cruise, a round trip from Copenhagen, offers an overnight stay in Stockholm, arriving in the morning and departing late in the afternoon the next day. Fares start at $2288 a person twin share.
The Upplev Mer rooftop tour in Stockholm costs SEK595 ($111) a person. Holland America Line also offers the tour as a shore excursion on days its ships dock in Stockholm.
Independent travellers must make advance bookings online. Participants must be taller than 150cm, weigh less than 120kg and have no cardiovascular or heart problems. Children under 18 must be accompanied by an adult.
FIVE MORE ROOFTOP TOURS
QUITO, ECUADOR Scamper across colonial buildings, church domes and private homes, followed by entrance to your choice of attractions. See quitocitytour.travel.
DUBLIN, IRELAND Croke Park Stadium has five viewing platforms with information about nearby sites provided by audio guide. See skylinecrokepark.ie.
KIEV, UKRAINE You can take this tour at night (on demand), and even sleep on a roof to see the sun rise over Vinogradar. See sputnik8.com.
ST PETERSBURG, RUSSIA For an extra cost, add a rooftop picnic or romantic dinner to heighten this experience. See sputnik8.com.
MELBOURNE, AUSTRALIA Take trams, stairwells, fire escapes and former hydraulic lifts, from Collins Street to the lower Yarra, the brothels of King Street and seaside docks. See melbournewalks.com.au.
- Sydney Morning Herald