Although it is never visited directly, the Battle Tower is referred to as being close to the Tohjo Falls in the anime.
In the manga
Tohjo Falls in Pokémon Adventures
In the Pokémon Adventures manga
In Chinchou in Charge, Misty, Brock, and Erika passed through the Tohjo Falls on their way to Johto. While crossing a rope bridge, Misty fell into a waterfall and saved a Krabby that was in trouble. After this, in Lovely Lanturn, Suicune came and challenged her. After battling with Misty, Suicune decided to go with her, and she, Brock and Erika continued their journey.
Interacting with the broken radio displays a message "There is a radio that no longer works". After battling Giovanni, the message changes to "You cannot turn on the radio. Giovanni must have left it here".
The Tohjo Falls seem to be similar to the real-life Niagara Falls, as both have two waterfalls serving as a well-known boundary between two places.
The Japanese name トージョウ shows that the location of the falls is a boundary between the two regions: at the end of カントー and the beginning of ジョウト. This naming convention is popular in Japan, as in 京葉 (Keiyō; named for 東京 and 千葉) and 東名 (Tōmei; named for 東京 and 名古屋). Its English name can also be taken as an anagram of Johto. Its Korean name is a portmanteau of 관동Gwandong (Kanto) and 성도 Seongdo (Johto), while its Chinese name is both an inversion of 城都 Chéngdū (Johto) and a portmanteau of 關都Guāndū (Kanto) and 城都 Chéngdū.