In which U.S. city did the internationally-renowned rock duo Hall and Oates meet?

Daryl Hall and John Oates, often referred to as Hall & Oates, are an American musical duo. Daryl Hall is generally the lead vocalist; John Oates primarily plays electric guitar and provides backing vocals. The two write most of the songs they perform, separately or in collaboration. They achieved their greatest fame from the late 1970's to the mid-1980's with a fusion of rock and roll and rhythm and blues.

Daryl Franklin Hohl (born in Pottstown, Pennsylvania, on October 11, 1946) and John William Oates (born in New York City, New York, on April 7, 1948) first met at the 'Adelphi' Ballroom in Philadelphia in 1967.

At the time they met, each was heading his own musical group, Hall with 'The Temptones' and Oates with 'The Masters'.

They were there for a band competition when gunfire rang out between two rival gangs, and in trying to escape, they ran to the same service elevator.

On further discovering that they were interested in the same music and that both were attending Philadelphia's Temple University, they started spending time together on a regular basis and eventually shared a number of apartments in the city.

One of the apartments they shared had "Hall & Oates" on the mailbox, which became the duo's name. It would take them another two years to form a musical duo, and three years after that, they signed to Atlantic Records and released their debut album.