Question: What is the second oldest arena in continuous operation in the US also known as?
Context: The Portland Exposition Building, also known as The Expo, is a sports and exhibition venue (convention center) building complex in Portland, Maine.  The complex includes five inter-connected buildings with 330,000 square feet of exhibition space and 10 meeting rooms.  The Center is adjacent to the Hadlock Field and the Portland Ice Arena.  Phish, Ani Difranco, Natalie Merchant, The Monkees, and Rusted Root have played at the venue.  It has also hosted trade shows and celebrations.  It has been used for the Maine Red Claws basketball team, Portland High School Bulldogs basketball games, and indoor track events.  In 2007, the Expo became the home of Maine Roller Derby. Naval Medical Research Unit Three (NAMRU-3) is a biomedical research laboratory of the US Navy located in Cairo, Arab Republic of Egypt.  NAMRU-3 is the oldest US overseas military medical research facility that has remained in the same location, and one of the largest medical research laboratories in the North Africa-Middle East region.  The laboratory has been in continuous operation despite periods of political tension and a seven-year lapse in U.S.-Egyptian relations (1967–1973) since 1942. Hill's Tavern is a historic building in Scenery Hill, Pennsylvania.  It was heavily damaged by a fire that started shortly before midnight on August 17, 2015.  For a period in the early 1900s, the inn was known as Central Hotel.  Now called the Century Inn, it had been the oldest tavern in continuous use on the National Road, until the fire brought an end to its 221 years of continuous operation.  The overnight facilities accommodated 23 overnight guests and the dining room could seat up to 140 guests.  The outdoor gazebo offered additional seating during the warmer months. Charles University, known also as Charles University in Prague (Czech: "Univerzita Karlova" ; Latin: "Universitas Carolina" ; German: "Karls-Universität" ) or historically as the "University of Prague" (Latin: "Universitas Pragensis" ), is the oldest and largest university in the Czech Republic.  Founded in 1348, it was the first university in Central Europe.  It is one of the oldest universities in Europe in continuous operation and ranks in the upper 1.5 percent of the world’s best universities. The San Francisco Motorcycle Club (SFMC) was founded in San Francisco, California in 1904.  It has been in continuous operation since its inception.  This makes it the second oldest motorcycle club in the United States, preceded only by the Yonkers MC of Yonkers, New York, founded in 1903. Fitzpatrick Stadium is a 6,300 seat multi-purpose outdoor stadium in Portland, Maine, USA.  It is located between Interstate 295, Hadlock Field baseball stadium, and the Portland Exposition Building, the second oldest arena in continuous operation in the United States.  It is located across the street from Deering Oaks, a public park listed on the National Register of Historic Places.  Formerly known as Portland Stadium, it was renamed in 1989 to honor James J. Fitzpatrick, one of the most respected figures in Maine athletic history. The Royal School for the Blind in Liverpool, England, is the oldest specialist school of its kind in the UK, having been founded in 1791.  Only the Paris school is older, but the Royal School for the Blind is the oldest school in the world in continuous operation, and the first in the world founded by a blind person, Edward Rushton, who was also an anti-slavery campaigner.  It was also the first school in the world to offer education and training to blind adults as well as children. The First Church of Hanover, also known as the First "Presbyterian" Church of Hanover, is located on Mount Pleasant Avenue in East Hanover, Morris County, New Jersey, United States.  Established in 1718 in what was then the British Province of New Jersey, it is a member of the Presbyterian Church (USA) and is one of the oldest churches in continuous operation in the United States.  The congregation's current building, constructed in 1835, is listed on the National Register of Historic Places. Mineola–Wisener Field Airport (FAA LID: 3F9) , a privately-owned public use airport also known as the Mineola Airport and Wisener Field, was established in 1917.  It has been under continuous operation by the same family since 1926.  It is considered the oldest privately operated public use airport in the state of Texas.  The field has been designated by the Texas Historical Commission as a Texas Treasure Business. The Williamson Diamond Mine (also known as the Mwadui mine) is a diamond mine 23 km northeast of Shinyanga in Tanzania; it became well known as the first significant diamond mine outside of South Africa.  The mine was established in 1940 by Dr. John Williamson, a Canadian geologist, and has been continuous operation since then, making it one of the oldest continuously operating diamond mines in the world.  Over its lifetime it has produced over 19 million carats (3,800 kg) of diamonds.  The Williamson mine, once owned by its namesake Dr. Williamson and later nationalized by the government of Tanzania.  Since February 2009 the mine is mostly owned by Petra Diamonds, with 75% ownership, the government of Tanzania owning the remaining 25%.
Answer: The Expo