Budapest is very proud of the fact that it was the first city “on the continent” that built metro line back in 1896. The “on the continent” phrase is used to say that it was the second metro in Europe, after London – which is not “on the continent” after all. Today there are three metro lines in the city, and although they have certain numbers they are usually known by their colors.
The oldest, Yellow line runs from Vörösmarty ter under the Andrassy út to the former site of the 1896 Millennium exhibition – today’s City Park – Városliget. It is basically a shallow cut-and-cover tunnel enabling the trams to run under the street level. The Red line stretches on east-west direction connecting the Déli train station on Buda side with Keleti station and eastern suburbs, while the Blue line stretches in north-south direction. All three lines meet at the Deák Tér. Various ticket types are available: Single ticket, Discount coupon books of 10 or 20 tickets, travelcards for 1, 3, 7, 14 and 30 days. Note that you need a separate ticket for each line.

Website: http://www.bkv.hu/english/metro/index.html