As soon as he stepped inside the East Village duplex 12 years ago, the theater director David Saint knew that it would be his next home.

“I saw about 20 apartments while I was looking to buy, and this was the last one,” he said. “The minute I walked in, I knew.”

What sold Mr. Saint on the brand-new penthouse, just off Union Square, at 123 Third Avenue and East 14th Street, was the wraparound terrace and its stunning cityscape and river views. He would eventually transform the terrace into his “little Garden of Eden” with fountains, obelisks, and potted trees, plants and flowers — not to mention a happening place for parties.