Aeolian Hall was a concert hall in midtown Manhattan in New York City, located on the third floor of 29-33 West 42nd Street (also 34 West 43rd Street, from the other side) across the street from Bryant Park.
 The Aeolian Building was built in 1912 for the Aeolian Company, which manufactured pianos. Located on the site of the former Latting Tower, which during the 19th century was a popular observatory, the 18-story building contained the 1,100-seat Aeolian Hall.
 The building stands next to the Grace Building.
The Sears Tower—Harvard Observatory is a historic astronomical observatory that is part of Harvard Observatory and is located at 60 Garden Street in Cambridge, Massachusetts.
 Now just a portion of the observatory's Building A, the Sears Tower is the oldest portion of the complex, designed by Isaiah Rogers and constructed in 1843.
 This structure is a square brick building, with a projecting cornice and a Greek Revival entrance framed by pilasters.
 The dome was equipped with a 15-inch telescope, the state of the art at the time.
The Olympic Tower, originally known as the United Shopping Tower, then the Northwestern Mutual Insurance Building, and later, the Olympic Savings Tower, is a historic 12-story office tower located in Seattle, Washington and listed on the National Register of Historic Places.
 It was originally built in 1929 at the Southwest corner of Third Avenue and Pine Street for the United Pacific Corporation under the control of Seattle investment firm Drumheller, Ehrlichman and White.
 It was designed by Henry Bittman who would also design additions to the building in 1939.
Vilnius University Astronomical Observatory is an astronomical observatory of Vilnius University.
 It was founded on 1753 by initiative of Thomas Zebrowski.
 The observatory is the fourth oldest observatory in the Europe.
 While the observatory is no longer able to make astronomical observations due to light pollution in Vilnius (observations are carried out at Molėtai Astronomical Observatory), it continues scientific research.
The Olympic Tower (German: Olympiaturm ) in the Olympic Park, Munich has an overall height of 291 m and a weight of 52,500 tons.
 At a height of 190 m there is an observation platform as well as a small rock and roll museum housing various memorabilia, which is signposted as "Rock Museum" outside the entrance.
 Since its opening in 1968, the tower has registered over 35 million visitors (as of 2004).
 At a height of 182 m there is a revolving restaurant, which seats 230 people.
 A full revolution takes 53 minutes.
 The tower also serves as a broadcast tower, and has one Deutsche Telekom maintenance elevator with a speed of 4 m/s, as well as two visitor lifts with a speed of 7 m/s which have a capacity of about 30 people per car.
 The travel time is about 30 seconds.
 The tower is open daily from 09:00 to 24:00.
Oxford Properties, established in 1960 is a global real estate owner, investor, developer and property manager with a portfolio of office, retail, industrial, multi-residential and hotel assets.
 Wholly owned by the Ontario Municipal Employees Retirement System since 2003, the company has offices In Toronto, New York, London and Luxembourg.
 The organization has 2,000 employees and over $40 billion of real assets that it manages for itself and on behalf of its co-owners and investment partners.
 Oxford’s portfolio of properties represents more than 50 million square feet of office, retail, hotel, industrial, land and multi-residential assets in key markets across Canada, the US and Europe.
 Some of its most recognized assets include Royal Bank Plaza, The Fairmont Banff Springs Hotel, Yorkdale Shopping Centre, Olympic Tower and The Leadenhall Building.
Solar Observatory Tower Meudon is a 36.47 metre tall tower built of reinforced concrete on the area of Meudon Observatory in Meudon, France, which has in its interior a spectrograph for examination of the sun.
 Solar Observatory Tower Meudon was built in 1964-65, and is a solar tower, a type of solar telescope.
 It has a shaft diameter of 6.6 metres.
 In a height of 30.57 metres it has an observatory floor with 18.4 metre diameter.
 The shaft of the tower consists of two concrete tubes which are separated by a 10 centimetre wide air spelt, in order to avoid wind induced vibrations.
The Elgin National Watch Company Observatory is a historic building in Elgin, in the U.S. state of Illinois.
 It was built in 1910 to serve the Elgin National Watch Company two blocks to the west.
 The two-story observatory provided data on time that was scientifically accurate to a tenth of a second.
 Manufacturers could then produce a more accurate watch.
 The observatory was an important part of the company's legacy, and they even changed their motto to reflect this.
 By 1950, the Elgin National Watch Company could no longer compete with wristwatch companies.
 The observatory was donated to a local school district and became known as the School District U-46 Planetarium/Observatory.
 The building was added to the National Register of Historic Places in 1994.
Olympic Tower is a 51-story building in Midtown Manhattan, in New York City on Fifth Avenue.
 It is between East 51st Street and East 52nd Street.
 The exact address is 641 Fifth Avenue.
 Built in 1975, it was constructed on a site that was occupied by a Best & Company Store that was built in 1947.
 It contains 225 condominium apartments and more than 250000 sqft of office space and retail space.
 Situated next to St. Patrick's Cathedral, it offers views of the cathedral's buttresses and Fifth Avenue.
 Upon construction, it became a prime real estate location for the glitterati of that time.
The Latting Observatory was a wooden tower in New York City built as part of the 1853 Exhibition of the Industry of All Nations, adjoining the New York Crystal Palace.
 It was located on the North side of 42nd Street between Fifth Avenue and Sixth Avenue across the street from the site of present-day Bryant Park.
 Conceived by Waring Latting and designed by architect William Naugle, the observatory was an octagonally-based, iron-braced wooden tower 315 ft high adjoining the Crystal Palace, with landings at three levels on the structure, allowing visitors to see into Queens, Staten Island and New Jersey.
 The tower, taller than the spire of Trinity Church at 290 ft , was the tallest structure in New York City from the time it was constructed in 1853 until it burned down in 1856.
 The tower's base was a 75-foot square, tapering to a top of six to eight feet.
 It could handle up to 1,500 people at a time.

Question: Which building, Olympic Tower or Latting Observatory, is no longer erect?
Answer: Latting Observatory