In addition to the wealth generated by the Buenos Aires Customs and the fertile pampas , railroad development in the second half of the 19th century increased the economic power of Buenos Aires as raw materials flowed into its factories. A leading destination for immigrants from Europe, particularly Italy and Spain, from 1880 to 1930 Buenos Aires became a multicultural city that ranked itself with the major European capitals. The Colón Theater became one of the world's top opera venues, and the city became the regional capital of radio , television , cinema , and theatre . The city's main avenues were built during those years, and the dawn of the 20th century saw the construction of South America's then-tallest buildings and its first underground system. A second construction boom, from 1945 to 1980, reshaped downtown and much of the city.
The trainsets are designed for high-speed services on Iberian gauge ( 1,668 mm ( 5 ft 5 21 ⁄ 32 in )) and high-speed ( 1,435 mm ( 4 ft 8 1 ⁄ 2 in )) lines; they can change gauge at low speed without stopping using Talgo's RD variable gauge system.  The carriages are constructed from aluminium and incorporate the Talgo Pendular passive pendulum tilting system,  are sealed against pressure differences for tunnel travel,  and have underframe air conditioning, individual audio systems and video displays, rotating and reclining seats and power outlets.