How to play Skyscrapers

Fill the grid with towers so every row and column holds each height once — and the edge clues count how many towers you can see. Also known as Towers, Skyline, Building puzzles.

▶ Play Skyscrapers ⊞ Open the solver

The rules

An N×N grid (here 4×4 to 7×7) is filled with towers of height 1 to N.
Each row and each column contains every height exactly once.
A clue outside the grid tells you how many towers can be seen looking along that row or column from that side.
A taller tower hides every shorter tower behind it, so you only see a tower if it is taller than all the towers in front of it.

Playing Skyscrapers on Puzzle Solvers

Choose a grid size (4×4 to 7×7) and a difficulty, then press New Puzzle.
Click a square and type a height, or use the keypad. Notes pencils in possibilities; Show all possibilities fills them in for you.
Click a clue to tick it off. A clue turns green when its line is full and correct, red if it is full and wrong.
Hint fills one square and explains the reasoning. Send to Solver opens the puzzle in the step-by-step solver; Send to Slate puts it on a Slate whiteboard; Print gives a clean copy on paper.

Open the Skyscrapers game →

Using the Skyscrapers solver

Choose the grid size, click each clue around the edge and type its number; type any given heights into their squares (or press Sample).
Press Solve. Step through with ◀ ▶: each step names its rule — edge clue, distance, single, line check — and highlights the squares it uses.
Candidates are shown in empty squares; the ones a step removes are crossed out in red.

Open the solver →

A worked example

In a 4×4 grid a row has clue 1 on the left and 2 on the right. Clue 1 puts the 4 in the first square. Looking from the right you must see exactly two towers: the last square, then the 4. So the last square must be the 3 — anything shorter would let a third tower show.

That row is now 4 _ _ 3, and the 1 and 2 can go either way — the column clues decide which.

Strategies

Clue 1 and clue N. A clue of 1 means the tallest tower stands right at that edge. A clue of N means you see every tower, so they climb 1, 2, 3 … N from that edge.
Distance from the edge. With a clue of c, the tallest tower is at least c−1 squares in, and the first square can be at most N−c+1 high. Write those limits in first.
Opposite clues. Clues at both ends of a line add up to at most N+1, and the tallest tower sits where the two views meet.
Try the line. When a row is nearly full, list the orders of the missing heights that still fit both clues. Often only one or two survive — anything they agree on can be filled in.
Ordinary singles. It is still a Latin square: a height that fits only one square of a row or column goes there.

Common mistakes

Counting every tower instead of only the ones taller than everything in front of them.
Forgetting that the clue reads from that side — a left clue is read left to right, a right clue right to left.
Leaving the Latin square rules until the end; they do most of the work in the middle of a puzzle.

Where it comes from

Skyscraper puzzles appeared in puzzle magazines in the 1990s and became popular in puzzle championships, where they are still a favourite. They are a Latin square, like Sudoku, with a city-skyline twist.

Frequently asked questions

Why can't I see a short tower behind a tall one?

Exactly like a real street: a shorter building behind a taller one is hidden. Count a tower only if it is taller than every tower in front of it.

Is there always one answer?

Yes. Every puzzle in the Skyscrapers game is checked to have exactly one solution, and Easy to Hard can be solved by reasoning alone.

Can the solver explain a puzzle from a book?

Yes. Type the clues and any given heights into the Skyscrapers Solver and step through every deduction.

What age is it good for?

4×4 puzzles suit ages 8 and up; 6×6 and 7×7 Expert puzzles challenge adults.

Keep going

All guides: How to play every puzzle and game.