London's licensed black taxi drivers argue there is a lack of regulation behind the new app.

Drivers in London faced a long wait as cabbies gathered in the tourist heartland of the city just after lunchtime.

The offending app: smartphone app Uber enables users to hail private hire cars from any location. The controversial piece of software, which is opposed by established taxi drivers, currently serves more than 100 cities in 37 countries.

As cabs filled the streets of London's West End, traffic began to grind to a halt. Not that you'd be able to tell the difference.

Cabs line Trafalgar Square under the watchful gaze of British naval hero Lord Nelson atop Nelson's Column.

As the demonstration began, black cabs of every colour began to move slowly through the West End.

Police attempt to keep traffic moving.

The demonstration was organised by the London Taxi Drivers' Association.

With the famous tower containing Big Ben in the distance, taxis bring the West End to a halt.

This traffic light on Whitehall may as well take the next couple of hours off.

The protest was aimed at Transport for London, the city's transit authority that regulates taxis and private hire services, including Uber.

Cabbies aren't opposed to technology or apps in general, with GetTaxi among the e-hailing apps getting the thumbs-up from drivers.

Demonstrators believe that Transport for London (TfL), the city's transportation agency, has let them down by allowing Uber to operate.

Protestors with a message for London Mayor Boris Johnson.

A show of solidarity from the The National Union of Rail, Maritime and Transport Workers (RMT), best known to Londoners for a recent string of tube strikes.

The demonstration saw thousands of taxis blockade streets.

Within less than half an hour after the demonstration's appointed start time -- or more accurately, stop time -- slow-moving traffic had turned into stationary traffic.

Protestors make their feelings plain about TFL.

A large police presence kept an eye on things, but the atmosphere was peaceful.

The international news media were also out in force.

Many cabbies also expressed dissatisfaction with another e-hailing app Hailo, which three weeks ago angered black cab drivers by adding private hire vehicles to its service.

Not all black cabs are black.

Cabbies train for years studying "The Knowledge," designed to etch every London streets into their brains.

Hailo has been rebranded as Failo by angry cabbies.

The only way you'll see anything more London today is if you pass out in a bowl of jellied eels.

Cabbies, journalists, and curious tourists mingle in the streets around Trafalgar Square.

Possibly not a real judge.

Coppers in choppers keep an eye on proceedings.

Best of British.

In less than an hour, the streets were gridlocked.

Luckily it's a nice day for a walk.

The ranks of the protestors were swelled by scooter-riding trainee taxi drivers, or "Knowledge Boys."

London's Waterloo Bridge was backed up too. Those buses aren't going anywhere.

Taxi drivers gather next to the Olympia Stadium in Berlin, Germany, to protest ride-sharing apps.

Police managed to keep Trafalgar Square itself clear, but streets for miles around weren't so lucky.

The London demonstration coincided with protests across Europe, such as here near Paris, France. French drivers slowed down to protest against the growing number of minicabs, known in France as Voitures de Tourisme avec Chauffeurs (VTC).

Passengers walk to Marignane airport in France after taxi drivers block the roads.

Hope he packed light.

Passengers forced to hoof it from Marignane airport.

This Italian taxi driver's vest reads "Don't take an illegal taxi, take a white regular taxi" at another demo, this time in Rome.

Italian drivers are unhappy with the growing number of minicabs and private hire cars, known in Italy as Car rental with driver (NCC).

Taxis drivers block the A9 highway heading to Spain at the toll gate of Le Boulou, outside Paris.

A taxi precedes demonstrators holding a banner during a strike action in protest of unlicensed taxi-type services in Barcelona, Spain.

Spanish taxi drivers hold a banner decrying "illegal" apps.

German taxi drivers gather next to the Olympia Stadium  in Berlin.

Berlin taxis are beige. Not quite as iconic as London's black or New York's yellow, but there you go.

Disgruntled drivers gather at Berlin's Tegel Airport. Approximately 1,000 taxis registered to participate in the protest.

German drivers protest against apps like Wundercar and Uber.

More drivers join the Tegel Airport demo.

Not everyone agrees with the cabbies: here, supporters of online ride-sharing apps hold up signs demanding an end to the taxi monopoly at a demonstration near Berlin's Olympia Stadium.

Taxis drivers block the highway outside Paris, near Roissy.

Taxis drivers in France make their feelings known.

More cars join the protest outside Paris.

While a large majority of the protest took place in Europe, there were also demonstrations around the world.

In Rio De Janeiro, Brazil, a day before the World Cup was set to begin, Taxi drivers and their supporters staged a small rally and partial road blockage as drivers protest Uber.

A police officer in Rio de Janeiro speaks with taxi drivers blocking traffic, asking them to move their vehicles.

Transport for London is referring Uber to Britain's High Court in an attempt to secure legal backing for its decision to allow Uber to operate. But with Uber and other e-hailing apps causing a storm of controversy in many cities around the world, it seems this story still has a long way to go.