Question: What was the length (to 3 decimals) of the road course at which the 1957 Pescara Grand Prix was held?

Context paragraphs:
Pescara Circuit: 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.

Reims-Gueux: The circuit Reims-Gueux was a Grand Prix motor racing road course, located in Gueux, 7.5 km west of Reims in the Champagne region of north-eastern France, established in 1926 as the second venue of the Grand Prix de la Marne.  The triangular layout of public roads formed three sectors between the villages of Thillois and Gueux over the La Garenne / Gueux intersection of Route nationale 31.  The circuit became known to be among the fastest of the era for its two long straights (approximately 2.2 km in length each) allowing maximum straight-line speed, resulting in many famous slipstream battles.

Saint Helier Circuit: The 1947 St Helier Circuit was a 5.149 km (3.199 m) Grand Prix road course in the town of Saint Helier, the capital of Jersey which is the largest of the North Sea Channel Islands (English Channel), hosting four consecutive Grand Prix events (official name: J.C.C. Jersey Road Race) from 1947 to 1950, the last one a Formula One non-championship round.  The circuit length remained largely the same over its four editions except for small variances within 100 meters.  British entries with Peter Whitehead, Reg Parnell, Raymond Mays, Peter Walker, Cuth Harrison, Leslie Johnson and David Hampshire among many others dominated the series, winning all events over many top drivers of the era.

2014 Australian Grand Prix: The 2014 Australian Grand Prix (formally known as the 2014 Formula 1 Rolex Australian Grand Prix) was a Formula One motor race that was held on 16 March 2014 in Melbourne.  The race was contested over 58 laps of the Melbourne Grand Prix Circuit and was the first round of the 2014 FIA Formula One World Championship.  It marked the début of new Formula One regulations which introduced 1.6 litre turbocharged V6 engines to the sport; the first such instance, since the 1988 Australian Grand Prix, that turbocharged engines have been used in Formula One.  It was the seventy-ninth race in the combined history of the Australian Grand Prix—which dates back to the 100 Miles Road Race of 1928—and the nineteenth time the event was held at the Melbourne Grand Prix Circuit.  The race also marked the thirtieth year that the Australian Grand Prix was run as a round of the Formula One World Championship.

1966 Singapore Grand Prix: 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.

1914 American Grand Prize: The 1914 American Grand Prize, held on February 28, 1914, was the third race of the 1914 Grand Prix season.  It was held at the Santa Monica Road Course in Santa Monica, California.  The Vanderbilt Cup, another Grand Prix race, was held on the same track two days earlier.  The Mercer of Eddie Pullen won by almost 40 minutes over the Marmon of Guy Ball.

2016 Grand Prix of Indianapolis: The 2016 Grand Prix of Indianapolis, officially known as the 2016 Angie's List Grand Prix of Indianapolis for sponsorship reasons, was the fifth round of the 2016 IndyCar Series season.  The race took place over 82 laps on the infield road course at Indianapolis Motor Speedway in Speedway, Indiana.  The race also served as part of the festivities surrounding the 2016 Indianapolis 500.  The car count for the race slightly increased from other races during the season due to some entries participating in the Indianapolis 500 electing to also run in the Grand Prix.

1957 Pescara 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.

Coppa Acerbo: 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.

1928 Australian Grand Prix: The 1928 Australian Grand Prix was a motor race held on the Phillip Island road course, on Phillip Island, Victoria, Australia on 31 March 1928.  Although now known as the first Australian Grand Prix, the race was actually staged as the 100 Miles Road Race and it did not assume the Australian Grand Prix title until some years later.  It was organised by the Victorian Light Car Club.

Supporting paragraphs: 1957 Pescara Grand Prix Pescara Circuit
Answer: 16.032 mi