Sofia now has 3 underground lines;  Line 1(red) runs from Slivnitsa (Lyulin) in the West of the city to the Business Park Sofia, via the city centre while the other, line 2(blue) runs from Vitosha in the South (Paradise Center) to Nadezhda and loops on itself to Sofia Airport Terminal 2. Line 3 runs from Haadzhi Dimitar in the north-east of the city to the suburb of Gorna Banya in the west. The underground is clean and efficient, though it does get crowded at peak times. Tickets now cost 1.60 leva for a single journey in one direction and can be bought from the ticket machines / booths at the entrance to the stations or you can directly use your bank card and just tap it on the scanning device at the turnstiles. The new charging system has been in place since the beginning of 2023 and means that for each journey (tap of the card) you will be charged 1.60 leva, however the maximum charge for any one day is 4 leva - so after your 3rd journey of the day you will not be charged even when you tap your bank card. When the ticket inspector checks you on the train, you just tap your same bankcard onto their mobile device... and somehow they see if you have paid.To use our bank cards in such a way has taken a huge leap of faith, but so far it seems to be working without too many issues, at least not that we have heard of.