In recent years, padlocks attached to bridge railings have become tokens of couples safeguarding their love and the locks have been showing up on bridges from Florence to Montevideo, from Paris to Moscow, from Denmark to China.
Until about a decade ago, however, those locks were confined to a single pedestrian bridge in the Serbian resort town of Vrnjacka Banja.
In the legend surrounding the bridge and the padlock tradition, a schoolmistress named Nada would meet her lover, a army officer named Relja, on the bridge where they pledged their love in the days before World War I. The soldier went on to fight the Germans at the Thessaloniki front in Greece, where he found a new love and married her. Nada is said to have died of sadness and grief.
Nada's tale of grief inspired young couples determined not to abandon one another to begin writing their names on padlocks and chaining them to the fence of the bridge where Nada and Relja swore their devotion. Serb couples then sealed their promises by tossing the keys into the clear spring-like Vrnjacka River below.
It remained a local phenomenon until Desanka Maksimovic, a noted Serb poet who died in 1993, heard the story of the bridge's lore and wrote one of her most beautiful poems "A Prayer for Love." The poem has stoked the romance of the bridge.
In Vrnjacka Banja "The Bridge of Love" is easy to spot. Unlike the 14 other bridges in this spa town, it's railings, from bank to bank, are covered in multiple chains of padlocks. All shapes and sizes, brass, steel, black and red. And each with its own message or date, some written with marker pen, others carefully engraved and etched. There are thousands of them.
"It is so romantic," said Slavisa, a 28-year-old soldier as he secured a padlock on the bridge to declare his love for his wife of two years, Danijela, 26. "It's so beautiful. It is original."
As the bridge's fame grew, it drew lovers from around the region and they have been joined by international tourists. The old bridge is now covered in lovers' graffiti along with a thick sheath of chains and locks.
While officials in Paris, Rome and elsewhere cut the locks off their bridges, city officials in Vrnjacka Banja do not want to tamper with tradition or love. And they do not fear the bridge will collapse under the weight of visitors' undying love and metal. Instead, no one dares remove the old padlocks so as not to court bad luck.
"We have 14 spare bridges on two different rivers. There is enough space for all the padlocks," says Dr. Dejan Stanojevic, a head of town's health spa. "We have so many keys in the river that soon we could have a dam that could lead to hydropower plant of love. We all know that love is a renewable source of energy," Stanojevic says with a smile.
Vrnjacka Banja rose to prominence in the early 20th century as a spa town on the strengths of mineral springs and baths that attracted patients seeking cures and drew most prominent political and artistic figures.
But today Vrnjacka Banja no longer tempts the prominent or the wealthy. But the "Bridge of Love" is still a draw, says Vesna, a street vendor who sells locks and keys on the spot for 500 dinars ($6.25) for a large lock or 100 dinars ($1.20) for the smallest.
"Buyers tell me the sound of iron closing on the bridge is a sound of commitment," says Vesna.
Couples take cell phone pictures on the bridge. On this day, Dusan and Branka marked their love with a lock, as did Rocky and Ceca and Isamu and Minoko from Japan.
Katja and Zoran from Slovenia are marking their 10th wedding anniversary and setting a new family tradition.
"We are doing something different, something that will show our descendents that we too were in love," Zoran explains. "We threw all the keys but one that we will keep together with our love bridge picture and GPS coordinates of the bridge."
"We will pass the complete file with today's date to our children and eventually to our grandchildren," Katja said. "We can only imagine how in 50, 60, 70 years our grandchildren or great grandchildren are coming here to search for a brass padlock with their ancestor's names engraved. Oh, it's so romantic."