The arrangement of stones at Stonehenge, likely the most famous Neolithic religious site, on the Salisbury Plain in southern England, results from several phases of construction that took place between 2,500 B.C. to around 2,000 B.C. The stones used in its construction came from two places. The bluestones, which form the inner, earliest, semicircle, came from the Preseli Mountains around 385 kilometres away. The larger sarsens, weighing up to 45 tonnes, were brought to Stonehenge from the Marlborough Downs, 30 kilometres to the north. (source)

At Baalbek, 53 miles from Beirut in Lebanon, stand the ruins of several Roman temples that were constructed in the first century A.D. A massive stone wall surrounds the temples. At the western end of the wall lie three of the largest blocks of cut stone in the world; the largest is 64 by 14 by 12 feet and weighs around 800 tons. This block would have to have been cut from a quarry almost a mile away, transported to Baalbek, and may have had to have been lifted up to 25 feet in the air in order to be placed in its final position. Few modern industrial cranes are capable of such a feat; however, the stones are placed so precisely, it is impossible to insert the blade of a knife between them. It is not known how these stones were transported.

The Circus Maximus in Rome, after its rebuilding by Julius Caesar, could accommodate 150,000 people. It was enlarged again in the days of the early empire to admit an additional 100,000. (source)

Due to rapidly increasing population, ancient Romans built tenement houses. They usually had three storeys and were made cheaply, of a kind of concrete. (source)

Modern archaeologists have not yet agreed on how large a crowd the Colosseum in Rome could hold in its glory days. One authority estimates 50,000, but around 45,000 is the generally accepted figure. (source)

There is a marble arch in Libya built in the year 164. It still stands, but has been covered with cement and turned into a grocery store.

A large number of ancient buildings in Rome that survived the fall of Rome and the many calamities that befell Rome in the Middle Ages were destroyed during the Renaissance, so that their building materials could be incorporated into new buildings. Michelangelo and others complained about this practice, but to no avail. (source)

It is reported that the Hagia Sophia (Church of the Holy Wisdom) in Constantinople cost 320,000 pounds of gold when it was constructed between 532 and 537. Even if that cost were exaggerated by a factor of ten, it was still a staggering amount of money for the Roman Empire to spend, as it was waging war simultaneously in Italy and Persia. (source)

Since 562, when the great dome of the cathedral of Hagia Sophia at Constantinople (modern-day Instanbul) was rebuilt following its collapse in 558, the cathedral has sustained what was, until recently, the largest self-supporting dome ever constructed, and that in an active seismic region. (source)

The Cathedral of Notre Dame in Amiens, built in the Middle Ages, covers 8,500 square yards and took 137 years to complete. When it was completed, the entire population of the city, around 10,000, could attend the same service.

The Taj Mahal in Agra, one of the world's most beautiful buildings, was built by the Moghul emperor Shah Jahan (1627-1659) as a mausoleum for one of his wives, Mumtaz Mahal, who, on her deathbed in 1631, extracted a promise from her husband to take care of her children and to build a suitable monument for her. Masons from northern India, calligraphers from Baghdad and Shiraz, and various specialists from all around the Muslim world designed and supervised building activities as well as planning the garden. The work was coordinated by Ustad Isa from Lahore. (source)

Until the British took over India, guards were posted at the Taj Mahal with a warning that any non-Muslim who tried to enter would be put to death. (source)

The Taj Mahal was scheduled to be torn down in the 1830s so that its marble facing could be auctioned off in London to the landed English gentry. Wrecking machinery was moved into the garden grounds and work was about to begin when word came from London to cancel the demolition. The first auction of marble facades of Indian buildings had been a failure, so tearing down the 200-year-old mausoleum would not be worth it. (source)

The Eiffel Tower, the best-known monument in Paris, was saved from demolition in 1909 only because there was an antenna, of great importance to French radio telegraphy, mounted at the top of the 984-foot tall structure. (source)

There are 2,500,000 rivets in the Eiffel Tower. (source)

The height of the 984-foot (usually) Eiffel Tower is over six inches higher in the summer than in the winter. (source)

The door at 10 Downing Street can only be opened from the inside.

In the small Italian town of San Gimignano during the fourteenth century, a lofty tower was the ultimate status symbol. The first turret was probably constructed for protection against street fighting between the Guelphs and Ghibellines, but soon, for reasons of prestige, other lords began building towers of their own, each trying to outdo his rivals. In a matter of a few years, 72 spires sprang up; fourteen still survive, giving San Gimignano its nickname, "the Manhattan of Tuscany". (source)

The smallest chapel in the world is on the grounds of a Benedictine monastery near Covington, Kentucky, in the United States. Not much larger than a telephone booth, it was built by Brother Albert Soltis for his personal use in 1878 and can accommodate no more than three people at once. (source)

The Empire State Building comprises over 10,000,000 bricks.

The Ice Hotel at Jukkasjarvi, Sweden, offers the ultimate in cold comfort—a building constructed out of ice where the average room temperature is −4°C. The beds are made from packed snow topped with spruce boughs and reindeer skins. The hotel melts every April and has to be rebuilt the following winter. (source)

The world's largest building without internal supports is the Goodyear Airship hangar, in Akron, Ohio - it has 55 million cubic feet of air. Clouds form in the top of the structure during sudden temperature changes, and it rains.

If the air conditioning at the Astrodome in Houston were turned off, it would rain inside the stadium due to humid air entering.

Around 250 people have fallen off of the Leaning Tower of Pisa since it was constructed in 1155.

The Vietnam War crypt at the Tomb of the Unknown Soldier in the United States' Arlington National Cemetery may remain empty permanently. No victim has turned up who was unidentified, fought in Vietnam, and who had more than 80% of his body recovered.

More damage has been done to Cleopatra's Needle, a hieroglyphic-covered granite obelisk, in the 125 years it has stood in pollution-filled, weather-beaten New York City than in thousands of years in dry Egypt. (source)

In Santos, Brazil, there is a thirty-two-storey tall building that serves as a cemetery. It is outfitted with over 14,000 tombs. (source)

Overlooking the town of Oban in Scotland is a replica of the Colosseum, known locally as McCaig's Folly. It was the idea of banker and self-styled art critic John Stewart McCaig who, after a trip to Italy, decided to recreate the glory of Rome in Scotland. It was intended as a museum and art gallery, but when McCaig died with only the shell built everyone lost interest. It now exists as a vast blackened cylinder and encloses a public garden. (source)

One quarter of the 10,300 glass panels in Boston's 60-storey Hancock Tower fell to the ground between 1971 and 1973.

In 1974, the U.S. Army Materiel Command ran a contest to name its new headquarters building. Around 500 entries were received. The entry that the contest committee decided on was "The AMC Building". (source)