Question: What is the length of the course raced on in the 1957 Pescara Grand Prix?

Context articles: Coppa Acerbo
BRM P133
Hideo Kanaya
Pescara Circuit
Doug Whiteford
1990 Spanish Grand Prix
1957 Pescara Grand Prix
1966 Singapore Grand Prix
1949 Roussillon Grand Prix
Olivier Chevallier

The Coppa Acerbo was an automobile race held in Italy, named after Tito Acerbo, the brother of Giacomo Acerbo, a prominent fascist politician.
 Following Italy's defeat in World War II, and the consequent demise of fascism, the race was renamed the Circuito di Pescara, and in some years was also referred to as the Pescara Grand Prix ("Gran Premio di Pescara").
 The race was run between 1924 and 1961 and over the years was held to a variety of vehicle class regulations and durations.
 In the Pescara Grand Prix formed a round of the Formula One World Championship, a race which still holds the record as having the longest circuit length ever used for a Championship event.
The BRM P133 was a Formula One racing car which raced in the 1968 and 1969 Formula One seasons.
 It was powered by a 3.0-litre V12 engine.
 Its best results were a second place at the 1968 Belgian Grand Prix, two third places at the 1968 Dutch Grand Prix and 1968 Canadian Grand Prix, as well as a fastest lap at the 1968 French Grand Prix all by Pedro Rodríguez.
Hideo Kanaya (Shinjitai: 金谷 秀夫 , Hideo Kanaya , February 3, 1945 – December 19, 2013) was a Grand Prix motorcycle road racer from Japan.
 Kanaya began his Grand Prix career in 1967 and won his first Grand Prix at the 1972 250cc German Grand Prix.
 In 1972, Kanaya and Jarno Saarinen raced the first four-cylinder, two-stroke Yamaha TZ 500 in the 500cc world championship.
 After Saarinen's death in the 250cc race at the Italian Grand Prix at Monza, the TZ 500 project was put aside and Kanaya raced only in the 250cc class.
 Kanaya's best season was in 1975, when he finished third in the 500cc world championship behind his Yamaha team-mate, Giacomo Agostini and MV Agusta's Phil Read.
 He also won the Macau Grand Prix in 1975.
The Pescara Circuit was a 16.032 mi road race course near Pescara, Italy.
 The staggering length was the longest of any open-wheel championship event.
Whiteford raced from the mid 1930s through to 1975 with a short period of inactivity during the 1960s.
 He was best known as a competitor in the Australian Grand Prix which he won three times in four years.
 He raced a Talbot-Lago T26 Formula One car which he used to win his second and third Grands Prix.
 His third win was at the first Albert Park street circuit which today hosts the modern Australian Grand Prix.
 Whiteford first contested the Australian Grand Prix in 1948 and continued to compete in the race regularly up to 1961 with a final appearance in the 1964 event.
 Whiteford also raced touring cars well into the 1970s.
 As a regular member of the Datsun Racing Team he was a fixture in small capacity Datsuns, usually as partner to John Roxburgh.
The 1990 Spanish Grand Prix was a Formula One motor race held on 30 September 1990 at Jerez.
 It was the 31st Spanish Grand Prix and the fifth and last time the Grand Prix was held at the Jerez circuit before moving to a new larger facility near Barcelona in Catalunya, though it was not the last time Formula One raced here; F1 returned twice in the 1990s for a race titled the European Grand Prix.
The 1957 Pescara Grand Prix was a Formula One motor race, held on 18 August 1957, at the Pescara Circuit near Pescara in Italy.
 It was race 7 of 8 in the 1957 World Championship of Drivers.
 The race, which was the only Formula One World Championship race at the track, was held at the longest ever circuit to stage a Formula One World Championship Grand Prix.
 The track is 25 km/16 miles long and is now part of the SR16bis on the coast of Pescara.
 It was also the first of the two consecutive Italian races, and after the subsequent race at Monza was complete, it became the first time that two Formula One World Championship races had been held in the same country in the same year.
The inaugural Singapore Grand Prix was held from the 9th to 11th in April 1966, on the Thomson Road Grand Prix circuit.
 Previous editions of the Grand Prix were held before Singapore gained its independence, and were not called "Singapore Grand Prix".
 The 1965 Malaysian Grand Prix was held on the same course, as part of the Malaysian Grand Prix event, as the 1966 Grand Prix of Singapore.
The 1949 Roussillon Grand Prix (formally the IV Grand Prix du Roussillon) was a Grand Prix motor race held at Circuit des Platanes de Perpignan on 8 May 1949.
 The Grand Prix was raced in two 50 laps sessions, with the final standing given by the addition of the both results.
Olivier Chevallier (born February 6, 1949 in Vendôme, Loir-et-Cher - April 6, 1980) was a French professional Grand Prix motorcycle road racer.
 His best year was in 1977 when he finished in sixth place in the 350cc world championship.
 His only Grand Prix victory came at the 1976 350cc Yugoslavian Grand Prix at Opatija.
 He was killed while competing at the Grand Prix of Le Castelet in 1980.
 Chevallier raced motorcycles designed and built by his brother Alain Chevallier, using Yamaha engines.