Question: Frank Ellis Boynton worked at a tourist attraction that stands today as one of the most prominent remaining examples of what?

Context paragraphs:
Excelsior Hotel, Christchurch: The Excelsior Hotel in 120 Manchester Street, Christchurch, originally the Borough Hotel, in recent years known as Excelsior Backpackers or New Excelsior Backpackers, was a Category I heritage building in central Christchurch.  It was designed by then most prominent architect, William Armson, and was one of the few remaining examples of his work in the city.  It was heavily damaged in the February 2011 Christchurch earthquake, and all but its western façade was demolished after the earthquakes.  The remaining part was demolished in April 2016.

Biltmore Estate: Biltmore Estate is a large (6950.4 acre or 10.86 square miles) private estate and tourist attraction near Asheville, North Carolina.  Biltmore House, the main residence, is a Châteauesque-style mansion built by George Washington Vanderbilt II between 1889 and 1895 and is the largest privately owned house in the United States, at 178926 sqft of floor space (135280 sqft of living area).  Still owned by George Vanderbilt's descendants, it stands today as one of the most prominent remaining examples of the Gilded Age.

Millennium Park: Millennium Park is a public park located in the Loop community area of Chicago in Illinois, US, and originally intended to celebrate the third millennium.  It is a prominent civic center near the city's Lake Michigan shoreline that covers a 24.5 acre section of northwestern Grant Park.  The area was previously occupied by parkland, Illinois Central rail yards, and parking lots.  The park, which is bounded by Michigan Avenue, Randolph Street, Columbus Drive and East Monroe Drive, features a variety of public art.  As of 2009, Millennium Park trailed only Navy Pier as a Chicago tourist attraction and by 2017 it had become the number one tourist attraction in the Midwestern United States.  In 2015, the park became the location of the city's annual Christmas tree lighting.

Troy Gas Light Company: The Troy Gas Light Company was a gas lighting company in Troy, New York, United States.  The Troy Gasholder Building is one of only ten or so remaining examples of a type of building that was common in Northeastern urban areas during the 19th century.  It was designed by Frederick A. Sabbaton who was a prominent gas engineer in New York State.  Originally sheltering a telescoping iron storage tank for coal gas, the brick gasholder house is an imposing structure from a significant period in the history of Troy.  For twenty-seven years the company held a monopoly on the manufacture of illuminating gas in the city.

Frank Ellis Boynton: Frank Ellis Boynton (July 10, 1859 – December 10, 1942) was a self-taught American botanist active in the Southeastern United States.  He worked at Biltmore Estate with his brother, Charles Lawrence Boynton, and Chauncey Beadle.  Boynton's dewberry, Rubus boyntonii was named in honor of Frank Ellis Boynton.

Cayman Turtle Farm: Cayman Turtle Centre is a conservation facility and tourist attraction located in the West Bay district of the Cayman Islands.  It is used for raising the endangered Green Sea Turtle.  Established in 1968 by a group of American and British investors as "Mariculture Limited", the centre was initially a facility used to raise the Green Sea Turtle for commercial purposes.  By raising the turtle in a farming operation, the investors could raise turtle-meat for consumption without depleting the wild population of the species.  Still in operation as a farm that breeds and raises turtles in order to sell product, the Cayman Turtle Farm has also become a research centre and tourist attraction.  Currently, the centre is a conservation project as well as the largest land-based attraction in the Cayman Islands.  The turtle centre welcomes more than 500,000 visitors annually.

Boldt Castle: Boldt Castle is a major landmark and tourist attraction in the Thousand Islands region of the U.S. state of New York.  Open to guests seasonally between mid May and mid October.  It is located on Heart Island in the Saint Lawrence River.  Heart Island is part of the Town of Alexandria, in Jefferson County.  Originally a private mansion built by an American millionaire, George Boldt, it is today maintained by the Thousand Islands Bridge Authority as a tourist attraction.

Charles Lawrence Boynton: Charles Lawrence Boynton (February 7, 1864–September 16, 1943) was an American botanist active in the Southeastern United States, working at Biltmore Estate with Chauncey Beadle and his brother, Frank Ellis Boynton.  The oak species "Quercus boyntonii" was named in honor of Charles Lawrence Boynton.

Tupou College: Tupou College is a Methodist boys' secondary boarding school in Toloa on the island of Tongatapu, Tonga. It is located on the Eastern District of Tongatapu near the village of Malapo.  The school is owned by the Free Weslyan Church of Tonga.  Established in 1866 by James Egan Moulton, it claims to be the oldest secondary school in the Pacific Islands.  Enrolment is some 1,000 pupils.  Tupou College was first established at Nuku'alofa at the location on which Queen Salote College stands today.  From there it moved to Nafualu, Sia'atoutai on the site where Sia'atoutai Theological College now stands.  In 1948, the school last moved to Toloa in the Eastern District of Tongatapu where it still stands today.  Tupou College's Brother school is Newington College which is in Sydney, Australia.

Mystery Spot: The Mystery Spot is a visual illusion–based tourist attraction near Santa Cruz, California, opened in 1941 by George Prather.  Visitors of the Mystery Spot experience gravity-defying demonstrations on the short but steep uphill walk.  The Mystery Spot is a popular tourist attraction, and gained recognition as a roadside "gravity box" or "tilted house" illusion.  At this roadside attraction, the laws of gravity and physics seem to disappear as balls roll uphill and people lean over past their toes without tumbling over.

Supporting paragraphs: Frank Ellis Boynton Biltmore Estate
Answer: the Gilded Age