Police and protesters clashed in Spain, Italy and Portugal as millions of workers went on strike to challenge to austerity policies.
As well as strikes across Europe, today has also produced figures that may convince people at the top that austerity is self-defeating.
David Cameron has promised to investigate the closure of a centre that has helped thousands of people overcome their disabilities.
Spanish police forcibly break up a sit down protest in central Madrid. Already very tense.
The 10.57am London to Brussels Eurostar train service was cancelled, with the company hoping to accommodate the affected passengers on the 12.57pm service.
"Further disruptions are possible throughout the day and customers are advised not to travel," Eurostar warned customers.
A General Strike is taking place across Europe today. Passengers please see our Travel Status for any disruptions: http://t.co/BYb8Jvqb
– British Airways
We are doing all we can to minimise the disruption to our customers.
Customers due to fly to or from Spain today can rebook to an alternate date free of charge. Customers on cancelled services can also take a full refund.
We are also looking at putting on larger aircraft to help as many customers as possible. We are advising customers to check ba.com for the latest flight information.
We apologise to our customers for any inconvenience caused by industrial action which is beyond our control.
Heathrow Airport has said 39 flights - nearly all involving Spain or Portugal - had been cancelled today at the west London airport, as a result of strike action across Europe.
Most people seem to have got the message that some flights were going to be axed and the terminals are operating smoothly.
Flight cancellations are never good news, but we do operate around 1,300 flights a day so the figure of 39 is a comparatively small one.
Madrid's main station completely deserted at the height of rush hour this morning. Nothing is moving.
There may be some delays today due to the strikes in continental Europe. Please check with your airline or airline website.
Due to strikes in Spain, Greece & Portugal tomorrow, some flights may be disrupted. Please check with your airline for the latest info.
In relation to any questions about the industrial action across Europe today, there are currently no delays from #bhx due to the action.
Air passengers endured travel misery today as UK airlines cancelled flights due to anti-austerity strikes across Europe.
British Airways had to axe eight round-trip flights between London and Madrid and Barcelona, as well as two return services to Lisbon in Portugal.
EasyJet cancelled some UK-Spanish services as well as more than 20 within-Europe flights.
Some other easyJet flights were badly delayed - with a London service to Thessalonaki in Greece delayed for three hours 40 minutes.
Passengers on an easyJet London to Athens flight faced a delay of two hours 30 minutes, while a Manchester-Athens flight was delayed for two hours 10 minutes.
Heathrow and Gatwick were among the UK airports where flights were delayed or cancelled.