The Plaza on DeWitt was the first building in the world to implement the tubular construction method later used for the World Trade Center. Originally called the DeWitt-Chestnut Apartment Building, and designed by Bangladeshi-Pakistani engineer Fazlur Rahman Khan while he was working for Skidmore, Owings & Merrill, it was completed in 1966 as a residential apartment building at 260 E. Chestnut Street in the Streeterville neighborhood of Chicago. The 43-story tower accommodates 407 residences and is the tallest building in Chicago to be clad in travertine marble. It was converted to condominiums in 1975. On the ground floor, a French bistro, Le Petit Paris, formerly Zaven's, serves traditional French cuisine.