Question: What company is headquartered at a casino formerly known as Vegas World?
Context: 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. Trump Entertainment Resorts, Inc. was a gaming and hospitality company that owned and operated the now shuttered Trump Taj Mahal hotel and casino, as well as the now shuttered Trump Plaza Hotel and Casino and the Trump Marina located in Atlantic City, New Jersey, United States.  Formerly known as Trump Hotels & Casino Resorts, it was founded in 1995 by Donald Trump, now 45th President of the United States, who has not had any formal role in the company since 2011, if not earlier.  The company filed for bankruptcy in 2004, 2009 and 2014.  It has been a subsidiary of Icahn Enterprises since 2016. Silver Sevens Hotel and Casino (formerly known as Terrible's) is a locals casino and hotel 1 mi east of the Las Vegas Strip, in Paradise, Nevada.  It has 370 rooms and a 35000 sqft casino. The Best Western Plus Casino Royale (formerly known as the Nob Hill Casino and Casino Royale) is a casino and small hotel on the Las Vegas Strip in Paradise, Nevada.  The casino caters to low rollers, and features low table minimums for roulette, craps, and blackjack. American Casino & Entertainment Properties (ACEP) is a casino holding company headquartered at the Stratosphere Las Vegas.  ACEP was a wholly owned subsidiary of American Real Estate Partners before it was sold to Whitehall Street Real Estate Funds, an investment arm of Goldman Sachs, in February 2008.  The company owns the following 4 casinos: Aquarius Casino Resort, Arizona Charlie's Decatur, Arizona Charlie's Boulder, and Stratosphere Las 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. 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. The Venetian Macao () is a luxury hotel and casino resort in Macau owned by the American Las Vegas Sands company.  The Venetian is a 39-story, casino hotel on the Cotai Strip in Macau.  The 10500000 sqft Venetian Macao is modeled on its sister casino resort The Venetian Las Vegas, and is the seventh-largest building in the world by floor area.  The Venetian Macao is also the largest casino in the world, and the largest single structure hotel building in Asia. Clarion Hotel and Casino, formerly known as Debbie Reynolds' Hollywood Hotel and Greek Isles Hotel & Casino, was near the Las Vegas Strip in Paradise, Nevada.  The hotel originally opened in 1970 as a Royal Inn, and also operated under the names Royal Americana Hotel and The Paddlewheel Hotel Casino before being purchased by Debbie Reynolds in 1992.  After Reynolds sold the property in 1999, it was briefly owned by the World Wrestling Federation, and was then sold and remodeled as the Greek Isles. The El Rancho Hotel and Casino (formerly known as The Thunderbird and The Silverbird) was a hotel and casino that operated on the Las Vegas Strip in Winchester, Nevada from 1948 to 1992.  After its closure, the El Rancho sat vacant for eight years while two companies made several attempts to reopen or replace the resort, which was eventually demolished in 2000, after a news report found the decrepit buildings to be in violation of health and safety regulations.  The site later became part of the land used for the un-opened Fontainebleau Resort Las Vegas.
Answer: American Casino & Entertainment Properties