Question: What store was founded in 1861 in Philadelphia and had Keith Chapman as its principal organist?

Context paragraphs:
John W. Bischoff: John W. Bischoff (27 November 1850 in Chicago – May 30, 1909 in Washington, DC) was a blind musician and composer.  Blind from age two, Bischoff went on to become a noted organist, compiler of musical collections, and composer.  His compilations included a significant number of his own works, and include "Gospel Bells" (1883), "God Be With You" (1880) and "Not Half Has Been Told" (1877).  He was the principal organist at the first Congregational Church in Washington from 1874 till his death in 1909.

Scott Turkington: Scott Turkington is the principal organist and choirmaster for Holy Family Catholic Church in St. Louis Park, Minnesota.  He is also on the board of the Church Music Association of America and directs one of several Gregorian scholas at the annual CMAA Colloquium on Sacred Music.

Phil Kelsall: Philip Julian "Phil" Kelsall MBE ALCM (born 13 July 1956) is an English theatre organist who has been principal organist at the Blackpool Tower Ballroom since 1977.  Born in Warrington he was inspired to learn the instrument by Reginald Dixon and was initially appointed as organist for the Tower Circus band aged 18 in 1975; he also deputised for Ernest Broadbent in the Ballroom itself.  This followed his attending Rossall School in Fleetwood, an independent day and boarding school where he was taught by Robin Proctor who subsequently became Director of Music at Cheltenham College.  After Ernest Broadbent's retirement, he was appointed Tower organist in 1977.

Keith Chapman (organist): Keith Chapman (1945-1989) was an American concert organist known best for his flair at playing in the symphonic style of organ performance, and particularly for his long and distinguished association (1966-1989) with the Wanamaker's Department Stores of Philadelphia as their principal organist of the Wanamaker Organ.

Chapman Entertainment: Chapman Entertainment was a United Kingdom television production company founded by Keith Chapman and Greg Lynn.

José Ximénez: José Ximénez, José Jiménez or Jusepe Ximénez (baptized 25 December 1601; died 9 August 1672) was a Spanish organist and the composer of 23 surviving works.  Born in Zaragoza, he became the assistant of Sebastian Aguilera de Heredia in 1620 and succeeded him as principal organist at La Seo after the latter's death in December 1627.  In 1654 he turned down an appointment to the royal chapel in Madrid, and seems to have spent the rest of his life in Saragossa.

Thomas Murray (organist): Thomas Mantle Murray (born October 6, 1943 in Los Angeles, California) is an American organist, known as an interpreter of Romantic organ music.  He is currently a Professor of Music and university organist at the Yale School of Music.  He is also Principal Organist and Artist in Residence at Christ Church in New Haven, Connecticut.

Wanamaker's: John Wanamaker, the founder of the store that bears his name, was unable to join the U.S. Army during the American Civil War because of a persistent cough.  Having been rejected from war duty, he ventured into business with his brother-in-law, Nathan Brown.  In 1861, they founded a men's clothing store in Philadelphia called Oak Hall.  Wanamaker carried on the business alone after Brown's death in 1868.  In 1876, Wanamaker purchased the abandoned Pennsylvania Railroad station for use as a new, larger retail location.  The concept was to renovate the terminal into a "Grand Depot" similar to London's Royal Exchange or Paris's Les Halles—two central markets, and forerunners of the modern department store, that were well known in Europe at that time.

Martin Ellis (organist): Martin Ellis is an American church, concert and theatre organist.  He is currently the organist for Rose City Park Presbyterian Church in Portland, OR.  He was Principal Organist and Assistant Music Director at North United Methodist Church, and Senior Staff Pianist/Organist, Staff Arranger and Orchestrator for the Indianapolis Children's Choir and Youth Chorale in Indianapolis, Indiana until August, 2014.  He works with Gresham High School (Oregon)'s Theatre Arts Department as their resident piano accompanist.  He also won the Oregon State Fair's Chili Cook-Off in 2014.

Daniel Cook (musician): Daniel Cook (born 7 September 1979) is an organist, conductor and singer.  He is Sub-Organist of Westminster Abbey, where he is principal organist to the Abbey Choir and Assistant Director of Music to Organist & Master of the Choristers, James O'Donnell.  Cook is Artistic Director of the Mousai Singers.

Supporting paragraphs: Keith Chapman (organist) Wanamaker's
Answer: Wanamaker's