The richest residents of New York City are living in multi-million-dollar Frankenmansions

When an apartment or penthouse isn't big enough for wealthy New Yorkers, they get creative.

In recent years, a number of them have combined multiple townhouses or building floors to create supersized homes, or Frankenmansions, as New York magazine's S. Jhoanna Robledo calls them.

To to construct these Frankenmansions, some prospective buyers purchase multiple buildings at once, while others approach their neighbors to offer multi-million-dollar buyouts. (In either scenario, they need the city's subsequent approval before combining properties.)

Check out these nine Manhattan Frankenmansions owned by big names- including Madonna, Sean Parker, and Sarah Jessica Parker - outlined below in red.