Palazzo Baldassini is a palace in Rome, Italy, designed by the Renaissance architect Antonio da Sangallo the Younger in about 1516-1519.
 It was designed for the papal jurist from Naples, Melchiorre Baldassini.
 The ground floor was used for shops or workshops, and the piano nobile consisted of private apartments.
Scala Regia (] and ] ; English: Royal Staircase ) is a flight of steps in the Vatican City and is part of the formal entrance to the Vatican.
 It was built by Antonio da Sangallo the Younger in the early 16th century, to connect the Apostolic Palace to St. Peter's Basilica, and restored by Gian Lorenzo Bernini from 1663 to 1666.
Giuliano da Sangallo (c. 1445 – 1516) was an Italian sculptor, architect and military engineer active during the Italian Renaissance.
 He is known primarily for being the favored architect of Lorenzo de' Medici, his patron.
 In this role, Giuliano designed a villa for Lorenzo as well as a monastery for Augustinian monks and a church where a miracle was said to have taken place.
 Additionally, Giuliano was commissioned to build multiple structures for Pope Julius II and Pope Leo X.
 Leon Battista Alberti and Filippo Brunelleschi heavily influenced Sangallo and in turn, he influenced other important Renaissance figures such as Raphael, Leonardo da Vinci, his brother Antonio da Sangallo the Elder, and his nephew, Antonio da Sangallo the Younger.
The Pozzo di San Patrizio (English: "St. Patrick's Well") is a historic well in Orvieto, Umbria, central Italy.
 It was built by architect-engineer Antonio da Sangallo the Younger of Florence, between 1527 and 1537, at the behest of Pope Clement VII who had taken refuge at Orvieto during the sack of Rome in 1527 by the Holy Roman Emperor Charles V, and feared that the city's water supply would be insufficient in the event of a siege.
 The well was completed in 1537 during the papacy of Pope Paul III.
Vatican City ( ; Italian: "Città del Vaticano" ] ; Latin: "Civitas Vaticana" ), officially Vatican City State or the State of Vatican City (Italian: "Stato della Città del Vaticano" ; Latin: "Status Civitatis Vaticanae" ), is a country located within the city of Rome.
 With an area of approximately 44 hectares (110 acres), and a population of 1,000, it is the smallest country in the world by both area and population.
 However, formally it is not sovereign, with sovereignty being held by the Holy See.
The town is home to the large Renaissance mansion or villa which dominates the surrounding country-side, Villa Farnese (or Villa Caprarola).
 Not to be confused with the Palazzo Farnese in Rome, it was initially built as a fortress, as the town and the surrounding area was a feud of the House of Farnese, by the cardinal Alessandro Farnese senio in 1530, according to a project of the architect Antonio da Sangallo the Younger.
 After only four years the project came to an halt when the cardinal was elected pope in 1534 under the name Paul III.
Antonio da Sangallo the Younger (12 April 14843 August 1546), also known as Antonio da San Gallo, was an Italian architect active during the Renaissance, mainly in Rome and the Papal States.
Palazzo Spada is a palace built on behest of Count Michelangelo Spada in the mid-sixteenth century and designed by Antonio da Sangallo the Younger.
 It currently serves as the town hall for the city of Terni.
 Alexandre de Rogissart wrote about the palace in the eighteenth century, remarking the beauty of its structure.
Giovanni Battista da Sangallo (1496–1548) was an Italian architect.
 He was the brother of the more famous Antonio da Sangallo the Younger.
San Giacomo Scossacavalli ("San Giacomo a Scossacavalli") was a church in Rome important for historical and artistic reasons.
 The church, facing the Piazza Scossacavalli, was built during the early Middle Ages and since the early 16th century hosted a confraternity which commissioned Renaissance architect Antonio da Sangallo the Younger to build a new shrine.
 This was richly decorated with frescoes, painted (among others) by mannerist artist Giovanni Battista Ricci and his students.
 The church was demolished in 1937, when Via della Conciliazione (the avenue leading to St. Peter's Basilica) was built and the piazza and central part of the Borgo rione were demolished.
 Many decorative elements still exist, since they were preserved from demolition.

Question: What country located within the city of Rome,is hime to a flight of steps built by Antonio da Sangallo the Younger in the early 16th century?
Answer: Vatican City