Opened in 1957, T-Centralen is the largest and busiest station in the Stockholm metro system. It is the only station which all three metro lines intersect. It was also the first station to feature artwork. The blue line’s T-Centralen station (opened in 1975) was designed by Per Olof Ultvedt (1935-2006). He was a Swedish sculptor, painter, illustrator, and graphic artis.