Problem: Voting results have been a consistent source of controversy. The mechanism of voting had also aroused considerable criticisms, most notably in season two when Ruben Studdard beat Clay Aiken in a close vote, and in season eight, when the massive increase in text votes (100 million more text votes than season 7) fueled the texting controversy. Concerns about power voting have been expressed from the very first season. Since 2004, votes also have been affected to a limited degree by online communities such as DialIdol, Vote for the Worst (closed in 2013), and Vote for the Girls (started 2010).
When did Vote for the Worst close?
The answer is the following: 2013

Problem: Strasbourg's status as a free city was revoked by the French Revolution. Enragés, most notoriously Eulogius Schneider, ruled the city with an increasingly iron hand. During this time, many churches and monasteries were either destroyed or severely damaged. The cathedral lost hundreds of its statues (later replaced by copies in the 19th century) and in April 1794, there was talk of tearing its spire down, on the grounds that it was against the principle of equality. The tower was saved, however, when in May of the same year citizens of Strasbourg crowned it with a giant tin Phrygian cap. This artifact was later kept in the historical collections of the city until it was destroyed by the Germans in 1870 during the Franco-Prussian war.
What revoked Strasbourg's status as a free city? 
The answer is the following: French Revolution

Problem: Greenware ceramics made from celadon had been made in the area since the 3rd-century Jin dynasty, but it returned to prominence—particularly in Longquan—during the Southern Song and Yuan. Longquan greenware is characterized by a thick unctuous glaze of a particular bluish-green tint over an otherwise undecorated light-grey porcellaneous body that is delicately potted. Yuan Longquan celadons feature a thinner, greener glaze on increasingly large vessels with decoration and shapes derived from Middle Eastern ceramic and metalwares. These were produced in large quantities for the Chinese export trade to Southeast Asia, the Middle East, and (during the Ming) Europe. By the Ming, however, production was notably deficient in quality. It is in this period that the Longquan kilns declined, to be eventually replaced in popularity and ceramic production by the kilns of Jingdezhen in Jiangxi.
What kilns were Longquan kilns replaced by in popularity and production?
The answer is the following: Jingdezhen in Jiangxi

Problem: The Cubs' current spring training facility is located in Sloan Park in |Mesa, Arizona, where they play in the Cactus League. The park seats 15,000, making it Major League baseball's largest spring training facility by capacity. The Cubs annually sell out most of their games both at home and on the road. Before Sloan Park opened in 2014, the team played games at HoHoKam Park - Dwight Patterson Field from 1979. "HoHoKam" is literally translated from Native American as "those who vanished." The North Siders have called Mesa their spring home for most seasons since 1952.
When did Sloan Park open?
The answer is the following:
2014