Expand the Tower of London
In the 13th century, Kings Henry III (1216–1272) and Edward I (1272–1307) extended the castle, essentially creating it as it stands today. Henry was disconnected from his barons, and a mutual lack of understanding led to unrest and resentment towards his rule. As a result, he was eager to ensure the Tower of London was a formidable fortification; at the same time Henry was an aesthete and wished to make the castle a comfortable place to live.
Effects: +1 yearly prestige / legitimacy

Start Poldering
By constructing a series of ♥♥♥♥♥, quays and windmills, the marches surrounding holland can be drained. This would expand the amount of avaliable farmland, but be a massive undertaking.
Effects: +5 tradepower, 20% cheaper development in Holland, Utrecht, Zeeland and Den Haag

Renovate the Al-hambra fortress
The Alhambra, The Red One, is a palace and fortress complex located in Granada, Andalusia, Spain. It was originally constructed as a small fortress in AD 889 on the remains of Roman fortifications, and then largely ignored until its ruins were renovated and rebuilt in the mid-13th century by the Nasrid emir Mohammed ben Al-Ahmar of the Emirate of Granada, who built its current palace and walls. It was converted into a royal palace in 1333 by Yusuf I, Sultan of Granada.
Effects: +100% local garrison size, +100% local defensiveness, +1 prestige / year

Finish the Tower of Pisa
Construction of the tower occurred in three stages over 199 years. Work on the ground floor of the white marble campanile began on August 14, 1173 during a period of military success and prosperity. This ground floor is a blind arcade articulated by engaged columns with classical Corinthian capitals.
Effects: +1 prestige / year, -1% prestige decay, -15% advisor costs

Contruct the Palace of Versailles
Louis XIV's expansion of the building was begun around 1661, with Louis Le Vau as architect. It was not completed until about 1715, having been worked on by architects including François d'Orbay, Charles Le Brun (interiors especially), Jules Hardouin-Mansart and Robert de Cotte. André Le Nôtre began the gardens and structures in them. There were a range of satellite buildings around the grounds.
Effects: +2 prestige / year, -0.05% autonomy / year, -15% advisor costs

Build the Branderburger Tor
The new gate was commissioned by Frederick William II of Prussia to represent peace. The Gate was designed by Carl Gotthard Langhans, the Court Superintendent of Buildings, and built between 1788 and 1791, replacing the earlier simple guardhouses which flanked the original gate in the Customs Wall.
Effects: +0.5 prestige / year, +10% Discipline, +15% local defensiveness

Expand the Petra
Petra lies on the slope of Jabal Al-Madbah in a basin among the mountains which form the eastern flank of Arabah valley that run from the Dead Sea to the Gulf of Aqaba. It was established possibly as early as the 4th century BC as the capital city of the Nabataean Kingdom. The Nabataeans were nomadic Arabs who invested in Petra's proximity to the trade routes by establishing it as a major regional trading hub.
Effects: -50% local development cost, +10 trade power

Convert the Hagia Sophia to an Imperial Mosque
In 1453, Constantinople was conquered by the Ottoman Empire under Mehmed the Conqueror, who ordered this main church of Orthodox Christianity converted into a mosque. Although some parts of the city of Constantinople were falling into disrepair, the cathedral was maintained with an amount of money set aside for this purpose. Nevertheless, the Christian cathedral made a strong impression on the new Ottoman rulers and they decided to convert it into a mosque.
Effects: +2 Missionaries, +0.5 Prestige

Construct the Machu Picchu
Most archaeologists believe that Machu Picchu was constructed as an estate for the Inca emperor Pachacuti (1438–1472). Often mistakenly referred to as the "Lost City of the Incas" (a title more accurately applied to Vilcabamba), it is the most familiar icon of Inca civilization. The Incas built the estate around 1450 but abandoned it a century later at the time of the Spanish Conquest.
Effects: -25% local development cost, +66% local tax generated

Restorate the Colloseum
The Colosseum is situated just east of the Roman Forum. Construction began under the emperor Vespasian in AD 72, and was completed in AD 80 under his successor and heir Titus. Further modifications were made during the reign of Domitian (81–96). These three emperors are known as the Flavian dynasty, and the amphitheatre was named in Latin for its association with their family name (Flavius).
Effects: +5% Discipline, +1 Army Tradition/year, +25% Local Tax Generated

Construct the Nyhavn
Nyhavn was constructed by King Christian V from 1670 to 1673, dug by Swedish prisoners of war from the Dano-Swedish War 1658–1660. It is a gateway from the sea to the old inner city at Kongens Nytorv (King's Square), where ships handled cargo and fishermens' catch. It was notorious for beer, sailors, and prostitution. Danish author Hans Christian Andersen lived at Nyhavn for some 18 years.
Effects: +10 Naval forcelimit, +25% Naval forcelimit modifier, +5 trade power

Construct Saint Basil's Cathedral
Pokrovsky Cathedral. It was built from 1555–61 on orders from Ivan the Terrible and commemorates the capture of Kazan and Astrakhan. It was the city's tallest building until the completion of the Ivan the Great Bell Tower in 1600.
Effects: +1 prestige / year, +2 True Religion Tolerance, +15% Religious Unity

Construct the Taj Mahal
Construction of the mausoleum was essentially completed in 1643 but work continued on other phases of the project for another 10 years. The Taj Mahal complex is believed to have been completed in its entirety in 1653.
Effects: +1 Prestige, +2 Heathen and Heretic Tolerance

Construct the Nidaros Cathedral
The Cathedral was built over the burial site of Saint Olav, the King of Norway in the 11th century, who became the patron saint of the nation, and is the traditional location for the consecration of the King of Norway. It was built from 1070 to 1300, and designated as the cathedral for the Diocese of Nidaros in 1152. After the Protestant Reformation, it was taken from the Roman Catholics by the new Church of Norway in 1537. It is the northernmost medieval cathedral in the world.
Effects: +1 true religion tolerance, +1 naval tradition / year, +1 prestige / year

Construct the Baghdad House of Wisdom
Destroyed in 1258, the House of Wisdom was a major intellectual center during the Islamic Golden Age. The House of Wisdom was founded as a library for private use by the Abbasid Caliph Harun al-Rashid (reigned 786–809) and culminated in prominence under his son al-Ma'mun (reigned 813–833) who is credited with its formal institution. Al-Ma'mun is also credited with bringing many well-known scholars to share information, ideas, and culture in the House of Wisdom.
Effects: +1 prestige/year, -15% technology cost, -10% idea cost

Construct the Great Wall of China
The Great Wall of China is a series of fortifications made of stone, brick, tamped earth, wood, and other materials, generally built along an east-to-west line across the historical northern borders of China to protect the Chinese states and empires against the raids and invasions of the various nomadic groups of the Eurasian Steppe. Several walls were being built as early as the 7th century BC; these, later joined together and made bigger and stronger, are collectively referred to as the Great Wall. Especially famous is the wall built in 220–206 BC by Qin Shi Huang, the first Emperor of China. Little of that wall remains. The Great Wall has been rebuilt, maintained, and enhanced over various dynasties; the majority of the existing wall is from the Ming Dynasty (1368–1644).
Effects: +50% local garrison size, +25% local manpower, +0.1 prestige / year §Yfor each wall segment

Reconstruct the Great Lighthouse of Alexandria
The Lighthouse of Alexandria, sometimes called the Pharos of Alexandria was a lighthouse built by the Ptolemaic Kingdom between 280 and 247 BC which has been estimated to be 100 metres in overall height. One of the Seven Wonders of the Ancient World, for many centuries it was one of the tallest man-made structures in the world. Badly damaged by three earthquakes between AD 956 and 1323, it then became an abandoned ruin. It was the third longest surviving ancient wonder (after the Mausoleum at Halicarnassus and the extant Great Pyramid of Giza), surviving in part until 1480, when the last of its remnant stones were used to build the Citadel of Qaitbay on the site.
+0.25 Prestige / Year, +20 Naval Forcelimit, +20 Local Trade Power

Reinforce Le Mont Saint-Michel
Le Mont Saint-Michel is an island commune in Normandy, France. The island has held strategic fortifications since ancient times and since the 8th century AD has been the seat of the monastery from which it draws its name. The structural composition of the town exemplifies the feudal society that constructed it: on top, God, the abbey and monastery; below, the great halls; then stores and housing; and at the bottom, outside the walls, houses for fishermen and farmers.
Effects: +200% local defensiveness, -0.5% monthly war exhaustion

Form the Escola de Sagres
The School of Sagres, also called Court of Sagres (in Portuguese Escola de Sagres) according to some historians was a group of scientific Portuguese personalities and techniques related to ocean navigation of the fifteenth century, formed around the infant Enrique, nicknamed the Navigator in Sagres near Cape St. Vincent, the southwestern end of the Iberian Peninsula, in the Algarve.
Effects: +25 colonial growth, -10% technology cost