The Sabine Hills is an area just north of Rome in Lazio in Italy. Perhaps most famous because its population fell victim to the “Rape of the Sabine women” by Rome, the hills have some interesting small towns.
http: //wikitravel.org/en/Sabine_Hills (link broken)
The Loggia dei Lanzi, also called the Loggia della Signoria, is a building on a corner of the Piazza della Signoria in Florence, Italy, adjoining the Uffizi Gallery. It consists of wide arches open to the street, three bays wide and one bay deep. The arches rest on clustered pilasters with Corinthian capitals. The wide arches appealed so much to the Florentines, that Michelangelo even proposed that they should be continued all around the Piazza della Signoria.
https://en.wikipedia.org/wiki/Loggia_dei_Lanzi
The Basilica di Santa Croce (Basilica of the Holy Cross) is the principal Franciscan church in Florence, Italy, and a minor basilica of the Roman Catholic Church. It is situated on the Piazza di Santa Croce, about 800 metres south east of the Duomo. The site, when first chosen, was in marshland outside the city walls. It is the burial place of some of the most illustrious Italians, such as Michelangelo, Galileo, Machiavelli, Foscolo, Gentile and Rossini, thus it is known also as the Temple of the Italian Glories (Tempio dell'Itale Glorie).
The Uffizi Gallery (Italian: Galleria degli Uffizi, Italian pronunciation: [ˌɡalleˈria deʎʎi ufˈfittsi]) is a museum in Florence, Italy. It is one of the oldest and most famous art museums of the Western world.
The Palazzo Pitti (Italian pronunciation: [paˈlattso ˈpitti]), in English sometimes called the Pitti Palace, is a vast mainly Renaissance palace in Florence, Italy. It is situated on the south side of the River Arno, a short distance from the Ponte Vecchio. The core of the present palazzo dates from 1458 and was originally the town residence of Luca Pitti, an ambitious Florentine banker.
Twain remarks that the gondola he rode in belonged to the Grand Hotel d' Europe, so I assume that is where he stayed while in Venice. I did not find a listing for this hotel on Google but I did find the Hotel Londra Palace of Venice operating in 1853.
The Patriarchal Cathedral Basilica of Saint Mark (officially known in Italian as the Basilica Cattedrale Patriarcale di San Marco and commonly known as Saint Mark's Basilica) is the cathedral church of the Roman Catholic Archdiocese of Venice, northern Italy.