It's not for the short of breath or weak-kneed, but the dizzying 360-degree vista of Paris from the Tour Saint-Jacques is one of the best-kept secrets of the French capital.
For one good reason: this flamboyant 16th-century Gothic tower, historically a stop on the pilgrimage route to Santiago de Compostela in Spain, has been closed to the public for most of its 500-year history.
Lacking a permanent license to receive public visitors, the 62-metre (203-foot) stone tower opened its doors on Friday for a two-month experiment.
It offers visitors stunning bird's eye views from the heart of Paris - provided they have the energy to walk up its claustrophobic 300-step spiral staircase and the 6 euro ($9.89) (3 euro for students and the unemployed) entrance fee.
From the zinc-topped terrace, the capital's most iconic landmarks compete for attention, from the neighbouring Conciergerie, Ile-Saint-Louis and Notre-Dame to the Pompidou Centre, the Eiffel Tower, Montmartre and La Defense.
"It's a fabulous view - you can see absolutely every monument. And look at all those rooftops, it's like an Impressionist painting," said 61-year-old Nadege Chaillou, who like other visitors "oohed" and "aahed" over the panorama.
Adorned with gargoyles and topped by a 3.5-metre statue of St. James the Apostle, the tower is all that remains of the medieval church of Saint-Jacques-de-la-Boucherie, pillaged and destroyed by French revolutionaries in the late 18th century.
The bell tower - which will be open until September 15 - was spared for its beauty and possibly to be used as a watchtower to spot the capital's frequent and deadly fires, curators say.
In the early 19th century, the bells were removed and Tour Saint-Jacques became a smoke-spewing "shot tower," or ammunition plant. Molten lead passed through a sieve and dropped from the top of the tower to land in a tub of water in the shape of a bullet. Later, it hosted a meteorological station until the 1990s.
The Tour Saint-Jacques underwent a meticulous 8.3-million-euro restoration from 2000 to 2009, during which time it was shrouded by scaffolding and decades of pollution were scrubbed from each of its stones.
It opened to the public for the first time in 2012, during France's annual Heritage weekend when visitors are invited inside public buildings of cultural and historical significance.
This year, the city of Paris granted a local association an exceptional permit to organize summertime visits from Friday to Sunday until Sept 15.
"We would like it to be open for a longer period each year," said Remi Riviere, head of the association. "If we get a lot of visitors this summer and nobody jumps from the terrace then hopefully the city will give us the green light."
Guided tours (in French) run every hour, from 10 am to 5 pm, accommodating groups of up to 17 people.