How did people build on a steep mountain?
Machu Picchu shows Inca buildings and terraces. Stepped surfaces make a slope usable differently from one continuous incline.
The short answer
At Machu Picchu, people built terraces, retaining walls and water routes on the steep mountain. Terraces are step-like flat areas on a slope. These structures helped them use the site and drain water.
Equal-sized Wusels study a Machu Picchu diorama with terraces and stone buildings. Artistically reduced diorama. Buildings and heights are not reproduced exactly; the view illustrates selected terrace shapes. AI-created illustration, not a photograph of nature.
What the diagram shows
The diagram simplifies the process. First compare its shapes and arrows. You can read its labels in larger text below.
Read the picture labels
These are the words and sentences from the diagram above. The full explanation follows below.
- Terraces create stepped crop surfaces
- Retaining wall holds soil
- Crop surface
- Stepped surfaces instead of one continuous slope
- Shape model: soil structure and water management are not fully shown.
An imagined Wusel scene
Puschel and Flauschi investigate
Puschel draws houses directly on a steep slope. Flauschi points to steps and water routes in the model. They add flat terraces and drainage routes. His plan now considers the difficult site as well as its houses.
Look closely
Flauschi points at a front terrace wall. Follow the steps upwards and find buildings above them. The diorama is an artistic approximation, not a complete architectural plan.
An example to help you understand
Fold firm paper into three broad steps and draw a sloping line beside them. Imagine a crop surface on each step. Which areas slope less? Compare with the model terraces. Paper illustrates shape only; it holds no real soil, designs no drainage and cannot explain all Inca building work. Do not build actual retaining walls or hillside works.
Try explaining it
What is a terrace on a steep slope?
Choose a), b) or c), then explain your choice.
- a)A step-like flatter area.
- b)A staircase consisting only of narrow steps for walking.
- c)A flat area hanging over the slope without support.
Show the explanation
Correct: a): A step-like flatter area.
At Machu Picchu, people built terraces, retaining walls and water routes on the steep mountain. Terraces are step-like flat areas on a slope. These structures helped them use the site and drain water.
Explore in more detail
Here you will find longer explanations and further details. You can explore them together.
1. An Inca site in Peru
Machu Picchu is in Peru’s Andes, a long South American mountain range. It lies about 2,430 metres above sea level and was built in the fifteenth century, the years 1401 to 1500. It belongs to Inca history. Buildings and fields occupy a steep ridge.
Checked against: [1]
2. Turn a slope into steps
Terraces are stepped surfaces made on a hillside. A retaining wall holds soil behind it, creating a less sloping surface. Machu Picchu has many terraces, including farming areas that provide places to grow crops. This differs from a free-standing balcony or patio also sometimes called a terrace.
Checked against: [2]
3. Plan buildings, fields and water
People had to connect buildings, paths and fields with the mountain landscape. Water channels also form part of this cultural landscape: an environment shaped by human use. We look for planned structures in the model. A beautiful mountain photograph alone does not explain life there. Planning involved removing water as well as supplying it. Surviving drainage outlets and channels reveal this work. Water accumulating behind a retaining wall adds pressure. Terraces therefore require more than attractive steps: foundations, walls and water routes must work together.
4. Not simply unknown to everyone
The site became much more widely known outside the region in 1911. That does not mean nobody had been there before: local people knew it. Specialists study the surviving traces, while some exact functions remain uncertain. The site and surroundings are protected as UNESCO World Heritage, a particularly important shared inheritance.
Checked against: [1]
An optional question for further exploration
You can use the longer explanation above. This is extra, not needed for the first quiz.
An extra question
Why do terraces help farming on a slope?
Discover the answer
They create stepped, less sloping surfaces. Retaining walls hold soil behind them. Parts of a steep slope become usable, although water management and further planning still matter.
Pictures and sources for adults
Sources for further reading
Facts checked against the specialist sources below on 12 October 2026. The Wusel scene is fictional; comparisons and simplified models are explicitly explained. Sources are in English.