Here are the key moments expected on the day Prime Minister Theresa May triggers Article 50:
At 08:00 The Prime Minister's top team will gather round the Cabinet table in No 10 Downing Street to discuss the contents of the letter that starts Britain's exit from the European Union.
12:00 Mrs May will appear at the Commons despatch box for the regular weekly session of Prime Minister's Questions. Once that finishes, sometime around 12:30, she will make a statement to MPs confirming the start of the two-year extraction process. At around the same time British ambassador to the EU Sir Tim Barrow will deliver the letter to European Council President Donald Tusk in Brussels. Once it has been accepted, Article 50 has been officially triggered.
12:45 As Mrs May finishes her formal statement, a text of the letter will be released. Mr Tusk will make a statement in the Europa Building to reporters soon after. Copies of the letter will be sent to the leaders of all other 27 EU member states.
16:15 European Parliament Brexit negotiator Guy Verhofstadt and its president, Antonio Tajani, will hold a press conference.
16:30 European Commission president Jean-Claude Juncker will take questions from reporters on other EU issues during a visit to Malta but is likely to be asked about the start of Britain's departure from the bloc.
Spending the past few days in Germany, I have found people here puzzled, offended, and feeling slightly bereft at the prospect of Britain's exit from the EU. They consider they are losing the one other major country that has a strong sense of financial and economic discipline, and they are right.