This line, called Földalatti, is the second oldest in the world after the London Underground. It was put into service in 1896, almost 80 years before the first line in Prague was launched. The line was designated a UNESCO World Heritage Site in 2002, not only because of the time of its construction, but also because of its architectural design. The stations are decorated with supporting columns with decorative elements made of cast iron or ceramic tiles in which the names of the stations are burnt.

The line, nowadays more commonly referred to as the M1 or Yellow Line, runs under the entire Andrássy Avenue and has a total of 11 stations. However, it is not a typical metro, as it is located just below the surface, so you only go down one imaginary floor and you are already standing on the platform. It is a regular part of public transport, so standard tickets apply.