4. London Heathrow Airport
London Heathrow Airport is the world’s fourth busiest airport by passenger traffic and busiest airport in the United Kingdom. It is also the busiest airport in the European Union in terms of passenger traffic and the second busiest in Europe in terms of traffic movements. It is located at 14 miles west of Central London. Passengers: 65,884,143 Operator: Heathrow Airport Limited.

Three Birmingham men have been arrested by counter-terrorism officers at Heathrow Airport.

The men from Small Heath and Alum Rock are suspected of being in possession of articles and documents with intent to use them for terrorism purposes.

The trio were detained by officers from the West Midlands Counter Terrorism Unit after arriving on a flight from Oman.

Police have confirmed that the arrests were pre-planned and intelligence led and were not made as a result of an emergency situation.