of June 2022 there are 20 lines in the network (numbered N0-N9, N11-N19 and N28), operated by two different companies: Tusgsal (es) and Mohn. The buses that are part of the Nitbus fleet operate between 22:20 and 06:00 (depending on the line; each is governed by different schedules), with a frequency of 3 buses per hour (that is, a frequency of 20 minutes). All Nitbus lines (except N0 and N19 routes) stop at the central square of Plaça de Catalunya, so it is possible to change lines. Madrid: Urban transport, i.e. journeys that take place within the municipal territory of Madrid, are operated by the Empresa Municipal de Transportes de Madrid (also known as EMT Madrid). There is a dense network of bus routes which operates 24 hours a day. Special services called the "N lines" are operated during nighttime. The buses in Madrid are the only public transport system available around the clock as the metro network closes down between 02:00 and 06:00 am. Night buses began in Madrid in October 1974 with 11 lines. From 2006 to 2013 while the Madrid Metro was being upgraded, a night bus named Búho Metro (es), or Metro Owl, also existed in Madrid whose network simulated the lines of the Metro, but above ground. This service only operated on Friday, Saturday, and holiday eves and line numbers were denoted by an 'L' prefix. As of May 2022, EMT Madrid operates a network of 28 night lines (es) (popularly called 'owls', or in Spanish) which operate from 23:45 to 06:00 (approx.). These routes are numbered N1 to N28. Their frequency depends on the time of night and the part of the city they travel to, but generally they run every 35 minutes on weekdays and every 15–20 minutes on weekends. Most night lines in the network depart from Plaza de Cibeles in the centre of Madrid, except the N25 and N26 which depart from Alonso Martínez. The buses departure times coincide with those of other lines to allow transfers. Night lines have the same fares as daytime lines, and the same tickets can be used. Intercity transport, i.e. journeys that go between different municipalities in the Madrid region, are operated by CRTM. The inter-urban buses (), commonly known as Green Owls (), travel further afield than the regular owl buses and connect Madrid with the cities of the periphery. As of June 2022