Which arena was not built during the NHL's expansion in the 1920s and 1930s?

Arena Gardens was not built during the NHL's expansion in the 1920s and 1930s. Instead, it has older roots, dating back to 1912, making it one of the earlier venues to host hockey games in Canada. As the NHL expanded during the 1920s and 1930s, new arenas were constructed to accommodate the growing popularity of the league and its teams, such as Maple Leaf Gardens, which opened in 1931, and Madison Square Garden, which was first opened in 1925. The United Center, however, opened much later in 1994, thus also not being part of that early expansion period.

In the context of this question, Arena Gardens stands out as the only venue built before the significant NHL expansion took place, showcasing its historical presence well before the league expanded in the early 20th century.