From what I heard the 40th floor Sky Lobby Observation Deck is no longer open to the public. When I went in 2014, it provided spectatar views of Downtown Dallas and I think it may have closed in 2018. The gardens at the Sky Lobby have also been removed. The Field Street Tower that will be built in a few years will have a public skylobby on the 16th floor, which is not high for the standards of Downtown Dallas. Therefore, while I understand Chase Tower is a private business, the owners should reopen the skylobby to the public with the gardens brought back so that it can compete with the new Field Street Tower.
https://www.citybiz.co/article/10644...three-decades/
https://en.m.wikipedia.org/wiki/Chase_Tower_(Dallas)
https://www.tripadvisor.com/ShowUser...las_Texas.html