Besides the well-known Egyptian Pyramids and Roman aqueducts, one interesting one I've recently learned about was about the columns in the Roman Pantheon were built: They were carved from single blocks of granite and then imported all the way from Egypt:
"The grey granite columns that were actually used in the Pantheon's pronaos were quarried in Egypt at Mons Claudianus in the eastern mountains. Each was 39 feet (11.9 m) tall, 5 feet (1.5 m) in diameter, and 60 tons in weight. These were dragged more than 100 km (62 miles) from the quarry to the river on wooden sledges. They were floated by barge down the Nile River when the water level was high during the spring floods, and then transferred to vessels to cross the Mediterranean Sea to the Roman port of Ostia. There, they were transferred back onto barges and pulled up the Tiber River to Rome. After being unloaded near the Mausoleum of Augustus, the site of the Pantheon was still about 700 meters away. Thus, it was necessary to either drag them or to move them on rollers to the construction site."
In the following picture we can see how tall the portico roof was expected to be and where it ended up:
So much of the Ancient world impresses me the more I learn. Seeing it amazes me more.
It's sad a lot of Ancient buildings or knowledge was destroyed as the next ruling party or ideology came to power.
Additionally, Pope Urban VIII had the bronze ceiling of the portico melted down to make cannons in the 1600's.
On the left side of the portico, you'll also notice that some of the columns don't match. If I'm remembering right, these were taken from a nearby Roman bath complex to repair earthquake damage to the portico. https://upload.wikimedia.org/wikipedia/commons/3/35/Pantheon...
All that said, it's still in remarkably good condition for being close to 2000 years old.
The Catholic Popes melted down anything they could find to create Christian things.
(in reference to Pope Urban VIII's family name, Barberini)
"On 22 April, Mehmed transported his lighter warships overland, around the Genoese colony of Galata, and into the Golden Horn's northern shore; eighty galleys were transported from the Bosphorus after paving a route, little over one mile, with wood. Thus the Byzantines stretched their troops over a longer portion of the walls." 
"The film production was an incredible ordeal,
and famously involved moving a 320-ton steamship
over a hill. This was filmed without the use of
He is one of my favorite directors now. I like his documentaries, and feature films. He has a distinctive style, and a great passion, which often comes through the documentaries where he interacts with the characters.
Amazing how long-lived many antique structures were. Apart from churches, I can't think of many 650 year old structures that are still used today.
You will find hundreds if not thousands of towns in Europe with whole streets full of 13th/14th century timber frame/fachwerk houses in the city centre.
There are also dozens if not hundreds of 12th/13th/14th century stone bridges still in use - usually such bridges didn't fall down, but were taken down and replaced with bigger and better ones as cities expanded.
Though ultimately the only reason to keep around old bridges or houses - just like churches - is nostalgia. The modern version could replace the old constructions at very low costs and with much lower maintenance and better comfort characteristics. Like antique cars, it is the quaintness and historic significance that keeps them up rather than their actual infrastructural superiority.
Those crafty tyrants, always up to something.