This penthouse is where Solomon Goldsmith resides during his time in New York and after his subsequent defection from Diva. It is located in the Midtown area of Manhattan, New York (otherwise known as the heart of New York City) and is exceptionally close to the iconic Empire State Building.
In the Anime
In Episode 43, Saya wakes up in Solomon's penthouse where she has been brought after she was rescued by Solomon. There Solomon pleads her to stay with him but Saya makes her way to the open terrace to leave. She resorts to jump from a great height but Solomon stops her. On the verge of convincing her - promising her a peaceful life, to take her to the most beautiful places on earth and even making her family his own; Solomon gets cut off by Hagi. Saya's stay in the penthouse is not prolonged and Solomon is once again left alone.