Play Skyscrapers Online

Fill each row and column with buildings 1–N. Border clues tell you how many towers are visible from that direction — taller buildings hide shorter ones behind them.

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Select a cell, then tap a number to place it

What Is Skyscrapers (Towers)?

Skyscrapers, also known as Towers, Buildings, or Hochhäuser, is a logic puzzle that combines Latin-square rules with a line-of-sight constraint. The puzzle first gained popularity in Japanese puzzle magazines and has since become a favourite among logic-puzzle enthusiasts worldwide.

You are given an N×N grid with numeric clues placed around the outside border. Each clue tells you how many “skyscrapers” (buildings of different heights) are visible when you look into the grid from that position. A taller building blocks the view of any shorter building behind it. Your goal is to fill every cell with a number from 1 to N so that each row and each column contains every number exactly once, and all the visibility clues are satisfied.

Rules of Skyscrapers

  1. Latin-square constraint: Fill every cell with a number from 1 to N. Each row and each column must contain every number exactly once — no repeats.
  2. Visibility clues: Numbers around the border indicate how many buildings are “visible” from that vantage point looking into the row or column.
  3. Taller hides shorter: A building with height h blocks the view of all buildings behind it with height ≤ h. Only the first building of each new “maximum height” is counted as visible.
  4. Blank clue positions: Not every border position has a clue. Positions without a number provide no constraint — you must deduce those rows/columns from other information.
  5. Unique solution: A well-formed puzzle has exactly one solution, reachable through pure logic with no guessing.

How to Solve Skyscrapers Puzzles

1. Clue of N Means Ascending Order

If a clue equals N (the grid size), every building must be visible. The only way that works is if the row or column is in strictly ascending order: 1, 2, 3, …, N. Fill those cells immediately.

2. Clue of 1 Means N Is First

A clue of 1 means only one building is visible — the tallest one (N) must be in the first cell. It blocks everything behind it. Place N in that position right away.

3. Use Opposite Clue Pairs

When both sides of a row or column have clues, their combination constrains the arrangement powerfully. For instance, in a 5×5 grid, clues of 2 and 4 on opposite ends of a row leave very few valid permutations.

4. Eliminate by Latin-Square Logic

Once you place a number in a cell, that number is removed from every other cell in the same row and column. This cascades — a single placement can trigger a chain of forced values across the grid.

5. Narrow Candidates with Visibility

If a border clue is 2, the first cell cannot be N−1 or higher unless N is before it (which makes N visible first). Work through what each clue forbids in the first few cells to eliminate candidates.

6. Check Remaining Permutations

For a partially filled row or column, enumerate the valid completions that satisfy both the Latin-square and visibility constraints. Often only one permutation works.

Grid Sizes & Difficulty Levels

  • 4×4 — Easy: Great for learning. Only 24 possible permutations per line, so clues resolve quickly.
  • 5×5: A meaningful step up — 120 permutations per line, more interplay between clues.
  • 6×6: The classic Skyscrapers experience. 720 permutations per line demand careful reasoning.
  • 7×7: For advanced solvers. 5,040 permutations per line, longer deduction chains, and subtle interactions.

Difficulty is controlled by how many border clues and given (pre-filled) cells are provided. Easy puzzles show most clues plus several givens. Medium puzzles remove some clues and givens. Hard puzzles provide minimal information, requiring deep logical reasoning.

Skyscrapers vs Other Logic Puzzles

  • vs Sudoku: Both are Latin-square puzzles, but Sudoku uses box constraints while Skyscrapers uses visibility clues from the border — a fundamentally different deduction style.
  • vs Futoshiki: Both fill an N×N grid with 1–N per row/column. Futoshiki uses inequality signs between adjacent cells, while Skyscrapers uses global line-of-sight counts.
  • vs Kakuro: Kakuro uses sum-based clues in a crossword layout. Skyscrapers uses count-based visibility clues around a square grid. Different constraint types but similar logical-elimination strategies.
  • vs Nonograms: Nonograms produce a picture from row/column run clues. Skyscrapers produce a numeric grid from visibility clues. Both reward systematic line-by-line analysis.

Frequently Asked Questions

Skyscrapers (Towers) is a logic puzzle on an N×N grid. Fill every cell with 1–N so each row and column is unique. Border clues tell you how many buildings are visible from that direction — taller buildings block shorter ones.
Start with extreme clues: 1 means the tallest building is first, N means ascending order. Use Latin-square elimination (no repeats in rows/columns) and opposite-clue logic to narrow down candidates.
Four sizes: 4×4 for quick warm-ups, 5×5 for a step up, 6×6 for the classic experience, and 7×7 for an advanced challenge.
Easy (most clues given, some pre-filled cells), Medium (fewer clues, more deduction), and Hard (minimal clues requiring advanced reasoning). Every puzzle has a unique solution.
Yes. “Skyscrapers” and “Towers” are the same puzzle with different names. Some publishers also use “Buildings” or “Hochhäuser.”

More Puzzle & Strategy Games

If you enjoy Skyscrapers, try these other free games on our site:

Futoshiki

Fill a grid with 1–N using inequality clues between cells.

Sudoku

The world’s most popular number puzzle — fill 9×9 with 1–9.

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