Question

What is the only city which has seen its NBA and NFL franchises win championships in the same building?

Answer

Chicago. The Bears and Portsmouth Spartans (now Detroit Lions) tied for the NFL title in 1932, so the league arranged the first-ever playoff game. Because of cold weather, the game was moved inside (to Chicago Stadium) and played on a narrow 80-yard field. Chicago won 9-0. Over a half century later, the NBA's Chicago Bulls won championships in the same building. By the way, the NFL playoff game probably never should have taken place. In 1932, the NFL did not count ties in its standings; the Packers, with a 10-3-1 record, using today's record-keeping finished with a better record than either the 6-1-6 Bears and 6-1-4 Spartans).