Poppenberg Observation Tower (German: Aussichtsturm Poppenberg "Poppenberg Observation Tower") is a steel German lattice observation tower that is used for observation, at the same time, for communication.
 It is a truss tower located in the summit of Poppenberg.
 It is one of the oldest steel lattice towers in Germany and was built in the year 1897.
 It was later on refurbished in 1994.
 The tower was built by the Nordhausen branch of the Harz Club.
 The tower was also named after Otto, Prince of Stolberg-Wernigerode.
 It has an antenna that is 33 metres long.
Atzelberg Tower (German: Atzelberg Turm "Atzel Mountain Tower"), also known as Atzelberg Observation Tower for long, was a 30.39 m German wooden lattice observation tower that was located on the summit of the 506.7 m mountain of Atzelberg.
 The Atzelberg Tower had a floor count of 6 floors including both the ground floor and the top.
 The Atzelberg Tower's top floor measured 30.39 m above sea level.
 The tower also had a roof which measured 31 m from the ground.
 The observation tower's top floor can only be reached through its 150-stepped staircases.
 The tower was used from the year of its construction, 1980, until 5 August 2008, when it was ravaged by fire that was caused by arson, as an observation tower on the top of the Atzelberg, which provided viewers and/or observers a good view of the surrounding areas.
Idarkopf Tower (German: Idarkopf Turm or Idarkopfturm ), also known as Idarkopf Observation Tower (German: Idarkopf Aussichtsturm ) for long, is a wooden German lattice observation tower on the summit of Mt. Idarkopf in the state of Rhineland-Palatinate.
 The observation tower on the 746 m mountain of Idarkopf has a total height of 28.50 m .
 Built in 1980, the tower was constructed according to a certain kind of specialized wooden frame and was designed through triangular sketch.
 Staircases are uncountable because of the vast number of steps.
 The roof, which contains the observation deck, is considered the highest accessible point in the whole area, providing a unique view of the town nearby.
The Gillerberg Observation Tower (German: Aussichtsturm Gillerberg or Gillerturm ) is a German steel lattice observation tower that was built in 1892.
 The Gillerberg Observation Tower is one of the oldest lattice towers in Germany and was renovated in 2004.
 The height of its observation deck is 15 metres above the ground.
Cordova Tower is an observation tower located on the north side of Lake Red Rock in Knoxville, Iowa.
 The tower features the world's longest and tallest continuous set of fiberglass stairs, ascending from the ground to the observation deck built atop a converted 100 ft by 15 ft stand-pipe water tower.
 The structure stands 106 ft tall 106 ft , making it the largest observation tower in the Midwest.
Tokyo Tower (東京タワー , Tōkyō tawā ) is a communications and observation tower in the Shiba-koen district of Minato, Tokyo, Japan.
 At 332.9 m , it is the second-tallest structure in Japan.
 The structure is an Eiffel Tower-inspired lattice tower that is painted white and international orange to comply with air safety regulations.
The Observation Tower Ahlbeck is a 50 metres tall observation tower with tree observation decks at Ahlbeck on the island Usedom in Germany.
 The Observation Tower Ahlbeck is a steel framework tower and carries on a fourth platform over the observation platforms and the top some aerials for mobile phone services.
The Tower of Unity (German: Turm der Einheit) is a 30 meter high observation tower on Heldrastein, a rocky mountain belonging to Treffurt in Thuringia.
 The tower of Unity has an unusual history and is also from unusual design, because it is additionally guyed by anchoring wires, although it is actually free standing.
 The tower of Unity was built in 1962 as transmitting tower for a radar station.
 At that time it was an open steel lattice tower additionally guyed with the radar facility on its top.
 The area of this tower was not accessible for tourists at those days as it laid in the restricted area of the former border between West and East Germany.
 In 1989, when the border was opened, the area became again accessible for the public and the desire developed to build on Heldrastein again an observation tower, as there was until 1952 an observation tower built of stones, the such called Carl Alexander tower there.
 In 1996 finally permission for the transformation of the radar tower into an observation tower could be received.
 In order to do this changes, which cost 205,000 DM, the radome on the top was removed and the tower body was covered with wood.
 In addition the tower got a stairway with 166 steps and an octagonal shelter at the tower basement.
Schomberg Observation Tower is a German observation tower that was constructed in 2005 and was finished in 2006.
 It is a steel truss tower that is used for observation, at the same time, used for mobile phone services.
 It has an observation deck which is 30 metres long and an antenna which is 60 metres long.
Tachū Naitō (内藤 多仲 , "Naitō Tachū" , 12 June 1886 - 25 August 1970) was a Japanese architect, engineer, and professor from Yamanashi Prefecture, Minami-Alps, Yamanashi.
 He was a father of earthquake-proof design and built many broadcasting and observation towers, including the Tokyo Tower.

Question: Tachū Naitō was the builder of which observation tower in the Shiba-koen district of Minato, Tokyo?
Answer: Tokyo Tower