Question: How high over the Las Vegas strip was the roller coaster in the building formerly known as Vegas World?

Context paragraphs:
Vegas World: Vegas World was a space-themed casino and hotel on Las Vegas Boulevard in Las Vegas, Nevada.  It was owned and operated by Bob Stupak, and was also signed as Bob Stupak's Vegas World.

El Rancho Vegas: El Rancho Vegas was a hotel and casino on the Las Vegas Strip.  It was located at 2500 Las Vegas Boulevard, at the southwest corner of Las Vegas Boulevard and Sahara Avenue, and opened on April 3, 1941.  Until 1942, it was the largest hotel in Las Vegas with 110 rooms.  On June 17, 1960, the hotel was destroyed by fire.  In 1982, the El Rancho Hotel and Casino formerly known as the Thunderbird and later as the Silverbird opened across the street from the former site of the El Rancho Vegas, creating some confusion.

Speed – The Ride: Speed – The Ride is a roller coaster currently in storage, it was located on the Las Vegas Strip at the now-defunct Sahara Hotel and Casino.  The coaster operated from April 28, 2000 to May 1, 2011.  The roller coaster is currently in storage at Akita Plaza.

The Roller Coaster: The Roller Coaster (formerly Manhattan Express), or sometimes Big Apple Coaster is the name of the roller coaster at the New York-New York Hotel and Casino on the Las Vegas Strip.  The ride's trains are themed to New York taxicabs.  It is the only roller coaster by TOGO still operating in North America.

Holy Cow Casino and Brewery: Holy Cow!  Casino and Brewery (formerly Foxy's Firehouse) was a locals casino and microbrewery on South Las Vegas Boulevard, north of the Las Vegas Strip, in Las Vegas, Nevada.  The property began in 1955 as Foxy's Deli, which operated until its closure in 1975.  A year later, the building was reopened as a casino named Foxy's Firehouse, which later closed in 1988.  Tom "Big Dog" Wiesner purchased the building and reopened it as the Holy Cow casino in 1992.  Wiesner added a microbrewery the following year, making the Holy Cow the first brewery to open in Las Vegas.  Wiesner persuaded the state to change its laws that had prohibited breweries from operating in Las Vegas.

List of tallest buildings in Las Vegas: The city of Las Vegas, Nevada and its surrounding unincorporated communities in the Las Vegas Valley are the sites of more than 160 high-rises, 42 of which stand taller than 400 ft .  The tallest structure in the city is the Stratosphere Tower, which rises 1149 ft just north of the Las Vegas Strip.  The tower is also the tallest observation tower in the United States.  Since the Stratosphere Tower is not fully habitable, however, it is not considered a building.  The tallest building in Las Vegas is the Fontainebleau Resort Las Vegas, which rises 735 ft and was topped out in November 2008.  This building, however, is currently on hold.  The tallest completed building in the city is the 52-story Palazzo, which rises 642 ft and was completed in 2007.

White Cyclone: White Cyclone (ホワイトサイクロン , Howaito Saikuron ) is a wooden roller coaster at Nagashima Spa Land in Mie Prefecture, Japan.  At 1700 m in length, White Cyclone is the third longest wooden roller coaster in the world, and is the longest wooden roller coaster outside of the United States.  Despite its length, White Cyclone is still considerably shorter than the 2479 m Steel Dragon 2000, the world's longest steel roller coaster, which is also at Nagashima Spa Land.  In addition to being the third longest wooden roller coaster, White Cyclone is the seventh tallest wooden roller coaster in the world and the fourth tallest wooden roller coaster outside the United States.  A single ride on the White Cyclone costs ¥1,000 (approximately $9 USD), and the ride is restricted to those individuals above 1.3 m in height; and those individuals under 54 years of age.

Naked City Las Vegas: Naked City is a neighborhood located in Las Vegas, Nevada north of the Las Vegas Strip The neighborhood is located at the northern end of the Las Vegas Strip, near the intersection of Las Vegas Boulevard and Sahara Avenue.  Due to the lack of commitment to updating the neighborhood, Naked City went from a modern neighborhood to a run down area full of poverty.  Naked City has been known to be one of the most dangerous neighborhoods in Las Vegas.

Stratosphere Las Vegas: The Stratosphere Las Vegas (formerly Vegas World) is a hotel, casino, and tower located on Las Vegas Boulevard just north of the Las Vegas Strip in Las Vegas, Nevada, United States.

High Roller (Stratosphere): The High Roller (also known as the Let it Ride High Roller), was a steel roller coaster constructed on top of a building 909 ft over the Las Vegas Strip.  It was the highest roller coaster in the world when compared to the surrounding terrain.  It was located on top of the Stratosphere Tower, Las Vegas, Nevada, which is the tallest free-standing observation tower in the United States.  The coaster was manufactured by S&MC GmbH Structures and Machines.

Supporting paragraphs: High Roller (Stratosphere) Stratosphere Las Vegas
Answer: 909 ft