Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The Budapest Metro is the rapid transit system in the Hungarian capital Budapest. It is the second-oldest underground metro system in the world after the London Underground. Its iconic Line 1, dating from 1896, was declared a World Heritage Site in 2002. The Metro consists of three lines, each designated by a number and a colour. Metro Line 4 is currently under construction; the first section is scheduled to open in 2014.