High-speed rail in Italy in the context of "Arezzo"

High-speed rail (HSR) is a type of rail transport network utilizing trains that run significantly faster than those of traditional rail, using an integrated system of specialized rolling stock and dedicated tracks. While there is no single definition or standard that applies worldwide, lines built to handle speeds of at least 250 km/h (155 mph) or upgraded lines of at least 200 km/h (125 mph) are generally considered to be high-speed.

The first high-speed rail system, the Tōkaidō Shinkansen, began operations in Honshu, Japan, in 1964. Due to the streamlined spitzer-shaped nose cone of the trains, the system also became known by its English nickname bullet train. Japan's example was followed by several European countries, initially in Italy with the Direttissima line, followed shortly thereafter by France, Germany, and Spain. Today, much of Europe has an extensive network with numerous international connections. Construction since the 21st century has led to China taking a leading role in high-speed rail. As of 2023, China's HSR network accounted for over two-thirds of the world's total.

The Florence–Rome high-speed railway line is a link in the Italian high-speed rail network. It is known as the ferrovia direttissima Firenze–Roma in Italian—meaning "most direct Florence–Rome railway" (abbreviated DD); this name reflects the naming of the Rome–Formia–Naples Direttissima opened in 1927 and the Bologna–Florence Direttissima opened in 1934. The line was the first high-speed line opened in Europe when more than half of it opened on 24 February 1977. It was completed on 26 May 1992, reducing the time of the fastest trains between the two cities to 1 hour and 20 minutes. The old line is referred to by Ferrovie dello Stato (the State Railways) as the Linea Lenta (meaning "slow line", abbreviated LL) to distinguish it from the parallel high-speed line.

In 2016 a contract was let for resignalling with ETCS level 2. The line is part of Corridor 1 of the European Union's Trans-European high-speed rail network, which connects Berlin and Palermo.