The Palazzo /pəˈlɑːtsoʊ/ is a luxury hotel and casino resort located on the Las Vegas Strip in Paradise, Nevada. It is the tallest completed building in Nevada. Designed by the Dallas based HKS, Inc., the hotel offers luxury in an Italian Renaissance ambiance. The hotel and casino are part of a larger complex (operated as one hotel) comprising the adjoining Venetian Resort and Casino and the Sands Convention Center, all of which are owned and operated by the Las Vegas Sands Corporation.
This all-suite hotel offers the largest standard accommodations on the Las Vegas Strip at 720 square feet (67 m 2) per guest room. The hotel complex is named the largest hotel in the world by the Guinness Book of World Records. 
In its first year of eligibility, The Palazzo was awarded the AAA Five Diamond Award for 2009, and has been awarded the honor every year since.  After 2014, The Venetian and The Palazzo no longer receive AAA Diamond awards, as the management has refused further AAA inspections. 
By 1949, the property was occupied by the Ottilia Villa Motel, the eight-room Park Lane Motel, and a restaurant named Maggie's.   The Carousel Motel opened on the property in 1953, and the adjacent Park Lane Motel was incorporated into the Carousel around 1954.  The Ottilia Villa was renamed as the Spanish Trail Motel in 1957.  
The Tam O'Shanter motel was built and opened in 1959,  on 1.5 acres (0.61 ha) of the land.  The motel was owned by Bernie Zeldin, and was named after Illinois' Tam O'Shanter Golf Course, where Zeldin frequently played.  The motel had 100 rooms,  and featured a distinctive neon sign resembling a tam o' shanter cap.  The sign was later donated to the city's Neon Museum.   The Spanish Trail Motel went out of business around 1960.  In 1962, it reopened as the Imperial 400 Motel. 
Zeldin declined numerous offers to purchase the Tam O'Shanter.  Billionare Howard Hughes attempted to purchase the Tam O'Shanter at some point, initially offering $3 million. However, Hughes was late in delivering the money, and Zeldin subsequently raised the price to $6 million. When Hughes was late again in delivering the money, Zeldin called off negotiations.   The Carousel Motel became the Sand Dunes Motel in 1973, and was demolished in 1998.  In 1990, the Imperial 400 became a Days Inn. In 1996, it became the Vagabond Inn. 
Before his death in June 1997,  Zeldin finalized a $12.5 million deal to sell the Tam O'Shanter to Sheldon Adelson's Las Vegas Sands, which later opened the adjacent Venetian resort in 1999.   Adelson was a friend of Zeldin.  Venetian officials purchased 11.4 acres (4.6 ha) of land, including the Tam O'Shanter, in October 1998.  Bernie Zeldin's daughter, Leah Zeldin, operated the Tam O'Shanter until its closure.   In December 2003, the Zeldin family was informed of the Venetian's plans to demolish the motel for a future resort.  While there were no specific plans for the new resort's theme or construction date, company officials wanted the motel demolished so the land could be prepared for the future project,  known as The Venetian Phase II, which would consist of a $1 billion resort with 3,000 rooms. 
Tam O'Shanter closed on January 12, 2004.   An asbestos-removal project for the motel took 19 days to complete. Tam O'Shanter was subsequently demolished on February 6, 2004,  to make room for The Palazzo.  The Vagabond Inn, which contained asbestos as well, was also demolished in February 2004. The asbestos-removal project cost between $500,000 and $1 million.  The land had also been occupied by the Las Vegas Kosher Deli,  as well as several small stores that were owned by the Venetian and were expected to close to make room for The Palazzo. 
Foundation work on the $1.6 billion Palazzo began in September 2004, without a groundbreaking ceremony.  As of February 27, 2006, the project had been under construction for over a year. Most of that time was spent digging the 4-story-deep hole to put in the underground parking structure. Then the building itself began to gradually rise upwards. The steel fabrication and erection was supplied by Schuff Steel Company. By November 2006, the hotel tower had reached the 35th floor. Construction of the ground floors, including the parking garage and shopping center, were well under way.
As of March 2007, the hotel tower's elevator core was complete, and the rooms area was rising to the top. The façade and windows were being installed on the lower floors. As of August 2007, the lettering on the side of the tower was finished and topped out.
As of December 20, 2007, the Palazzo was scheduled to open at least 1,000 rooms by December 28 in preparation for the Las Vegas New Year's celebration, America's Party. The casino and other areas of the Palazzo opened at 7pm on Sunday, December 30, 2007, after a delay of several days due to the Clark County permitting process.
Upon its completion, The Palazzo ‒ its total floor area covering 6,948,980 square feet (645,581 m 2) ‒ displaced the Pentagon as the largest building in the United States in terms of floor space by a margin of about 383,000 square feet (35,600 m 2 ). 
The structural engineering was done by Walter P Moore Engineers and Consultants. Parts of the resort were opened to the general public on December 30, 2007.  The official grand opening took place on January 17, 2008.
St. Regis Residences at The Palazzo
The St. Regis Residences at The Palazzo is currently under construction.  It will be a 270-unit condominium tower addition and The Venetian complex's first residential offering. The high-rise tower is being built on top of the 90,000-square-foot (8,400 m 2) building that houses the Barneys New York apparel store. On September 4, 2008, Las Vegas Sands announced that it had come to an agreement with Starwood Hotels & Resorts to operate the condo tower as a signature branch of The St. Regis Residences with all hallmarks of the St. Regis brand offered to residents. However, construction on that tower has been halted due to the Great Recession.  
The $ 1.8 billion resort features a lobby where guests from the street arrive beneath a 60-foot (18 m) glass dome with a two-story fountain. Those approaching from The Venetian make the transition through a towering octagonal structure and garden, itself topped by a glass-and-iron dome. Visitors to The Palazzo using the underground parking structure can take elevators or escalators from the underground garage and arrive in the center of the property's casino.
The Palazzo Casino, like some other casinos on the Strip, operates under the license of a related casino—in this case The Venetian's license. The resort's 642-foot (196 m) high hotel tower features 3,068 all-suite rooms and 375 concierge -level suites.
The Palazzo is reported to be the eleventh largest building in the world in terms of available floor space and is also currently the second-largest building in the Western Hemisphere.
Dal Toro Las Vegas
The Las Vegas Car Museum is inside the multi-story Dal Toro restaurant, and features displays of exotic automobiles from automakers including Bugatti, Spyker, Saleen, and Koenigsegg. The 20,000-square-foot (1,900 m 2) showroom is decorated with Italian-imported marble and tile flooring, rich leather wall coverings, and vibrant artwork. The space was originally a Lamborghini Las Vegas dealership. The restaurant stopped using the automaker's trademark after a lawsuit was filed. 
Grand Canal Shoppes at The Venetian and The Palazzo
Features upscale boutique stores from the likes of Ralph Lauren, Jimmy Choo, Fendi, Cole Haan, Piaget, Diane von Furstenberg, Chloè, Bottega Veneta, Bvlgari, Michael Kors, Burberry, Christian Louboutin, Catherine Malandrino, Anya Hindmarch, Charriol, and others. It also features an 85,000-square-foot (7,900 m 2) Barneys New York.
- An under construction Palazzo was the setting for an early scene of Ocean's Thirteen.
- The game show Wheel of Fortune taped four weeks of shows at the Palazzo in July 2009,. Two weeks of shows aired in September 2009 and the other two aired in February 2010. Also, the show taped six weeks of shows in July 2013 starting with the Season 31 premiere airing on September 2013.
- The construction of Palazzo was featured on the Science Channel's Build It Bigger.
- Was the shooting location featured in episode 18 of the fifth season of MTV's The Hills as well as a setting for the dramatic season three finale.
- The hotel is the main location in the final novel in the Vegas book series Palazzo, where American currency is attempted to be transferred to Milan, Italy, for a drug deal.