A look at today's modern sports arenas reveal an array of architectural wonders: retractable roofs, scenic downtown panoramas and first-class amenities have become commonplace. More than half of MLB's 30 stadiums were opened after the turn of the 21st century, while only five predate the 1970s. In the NFL, 17 out of 30 stadiums opened in the year 2000 or later, and just two—Lambeau Field (opened 1957) and Soldier Field (1924)—were opened before the 1970s.
On this day in 1965, the revolutionary Houston Astrodome opened its doors for the first time and ushered in a new era of professional sports stadiums.