Mexico City is served by the ''Sistema de Transporte Colectivo'', a  metro system, which is the largest in Latin America. The first portions were opened in 1969 and it has expanded to 12 lines with 195 stations. The metro transports 4.4 million people every day. It is the 8th busiest metro system in the world, behind Tokyo (10.0 million), Beijing (9.3 million), Shanghai (7.8 million), Seoul (7.3 million), Moscow (6.7 million), Guangzhou (6.2 million), and New York City (4.9 million). It is heavily subsidized, and has some of the lowest fares in the world, each trip costing 5.00 pesos (roughly US$0.27) from 05:00 am to midnight. Several stations display pre-Columbian artifacts and architecture that were discovered during the metro's construction.  However, the metro covers less than half of the total urban area. The Metro stations are also differentiated by the use of icons and glyphs which were created for the illiterate, a unique system that has become iconic characteristic of Mexico City. Each icon was developed based on historical (characters, sites, pre-Hispanic motifs), linguistic, symbolic (glyphs) or geographic references. A complementary system of icons was used for the Metrobús (BRT) stops.