Berlin is a year round destination with a festival, parade or fair happening during most months - from the International Film Festival in February, Beer Festival in August (or the Flamenco Festival for the more energetic), through to the Christmas Markets running from the end of November until the end of the year. The weather varies from being surprisingly hot in summer to fiercely cold during the winter.
Note: flight, boat, train and bus timetables change constantly, and airlines come and go, so please do not rely solely on this information for your travel planning. Check with relevant companies, or a flight search engine like Skyscanner, first.
From the UK to Berlin:
Air Berlin flies from London Stanstead and Jersey to Berlin Tegel.
British Airways flies from London Heathrow to Berlin Tegel.
BMI flies from London City to Berlin Tegel.
easyJet flies from Bristol, Glasgow, Liverpool, London Gatwick and London Luton to Berlin Schönefeld.
Lufthansa flies from London City to Berlin Tegel.
Ryanair flies from London Stanstead and East Midlands to Berlin Schönefeld.
From Ireland (Eire) to Berlin:
Ryanair flies from Dublin to Berlin Schönefeld.
From rest of Europe to Berlin
Air Berlin flies to Berlin Tegel from most European countries, including minor airports.
From UK to Berlin:
It's easy to travel from London to Berlin by train. Take an early evening Eurostar from London to Paris or Brussels (2 ½ hours), then the overnight sleeper train to Berlin, city centre to city centre, arriving in time for breakfast. Some sleepers even have a private toilet and shower. For more details, see Seat 61.
BY TRAIN / METRO
The network of U-bahn (underground) and S-bahn (Schnellbahn / overground) lines is efficient and widespread. You can get free maps, and a family- or multi-day pass, at the airport.
Reasonable network and the traffic flows better than, for example, in London. Useful routes include Ku'Damm to centre. Fares are usually around €2-2.50, but you can get a day pass for around €6-7 (in 2009).
Tourist boats (like Parisian bateaux mouches) ply along the Spree between Tiergarten and Museum Island. Jump off points include the Haus der Kulturen to the west, Friedrichstrasse in the middle, and Bruckenstrasse in the southeast.
Cheap and plentiful. For most city centre journeys allow €7-10. For short trips, hail a cab and ask for a Kurzstrecke (€3 in 2009, max 2km, then you get booted out!).
There are plenty of hire shops; or, if you have registered first and given credit card details as aguarantee, find a red bicycle with DB on it, and phone the code to unlock it, and again at your destination (you can leave it almost anywhere). It costs €0.07/min, less if you have a railcard.
Only in Berlin will you find an octopus with wheels ... and 8 saddles for you and your friends to pedal yourselves along Unter den Linden. Assuming, of course, the chap in the middle can steer.