several Island Councils (cabildo insular). The prefix denotes the island, and identifiers are usually white on blue background. Castile-La Mancha Another community that has recently started building its own high capacity road network, Castile-La Mancha has completed one autovía and has at least five more in varied states of advanced planning and building. In the flat La Mancha, relief does not usually require costly tunnels and bridges, though the region does contain several nature reserves including the Tablas de Daimiel National Park wetlands. Highway identifiers are white on blue background. *: in construction — †: planned Castile and León The largest community in Spain by land area, Castile and León has a dense road network, but until recently most of its highways had been part of the national system. The terrain is varied, from the plains of the Meseta to the rugosities of the Montes de León, and archeological remains abound. Regional highways are renamed to A-nnn, always with three digits to avoid clashes with the national network, but usually keeping the original number of the upgraded regional road CL-nnn. Identifiers are white on blue background. *: in construction — †: planned Cantabria The only community without a high-capacity network of its own, Cantabria is severely held back in such a development by a highly mountainous terrain that multiplies the cost of building any kind of expressway. Thus, its population is served by the national highway network supplemented by regional conventional roads. Catalonia The second most populated community in Spain, Catalonia has a thorough regional road network, with several highways managed by the Generalitat de Catalunya. Also, the state-owned highways previously known as A-16 through A-19 were transferred to the Catalan government and renamed according to the new regional guidelines enacted in 2004. Highway identifiers are white on blue background. *: in construction — †: planned Extremadura A sparsely populated community, Extremadura has a terrain that can be considered favourable for a regional highway plan, as the interior is mostly flat. However, the fact that its northern and north-eastern borders are blocked by mountain ranges with typical elevations of over the main mesa, combined with the mentioned demographics of the territory (Extremadura ranks the 5th community in Spain by land area, but only the 12th by population, and none of its cities reach 200,000 inhabitants) has traditionally limited the penetration of even the national highway network. Nevertheless, the community is