Mt. Holly Mansion Map & Wing Layout

Updated May 14, 2026 · 7 min read · Reference

Blue Prince's Mt. Holly mansion is a 9-column by 5-row grid with the Entrance Hall fixed at the bottom-center cell. Room placement is randomized each run, but grid dimensions, wing boundaries, and underground access points are fixed. This page gives you the spatial mental model.

The Mt. Holly Grid

East Wing

The East Wing is the right-hand third of the grid (columns 7–9). Rooms more likely to spawn here:

• Vault — almost always in the rightmost column. The 4-digit code 4558 opens it.
• Office — one of the three Vault letter rooms.
• Library — second Vault letter; bookmarked page.
• Workshop — required for crafting the Telescope Lens.

West Wing

The West Wing is the left-hand third (columns 1–3). Rooms biased to spawn here:

• Observatory — purple-rarity card. Solving it gives the Architect's Diagram, condition #2 for Room 46.
• Conservatory — Step regen; high value.
• Drawing Room — contains the partial 45-room map.
• Room 46 outline — appears on the far wall when all three conditions are met.

Atrium & Central Spine

The Atrium row is the middle horizontal corridor (row 4 from the bottom). It connects East and West wings. Rooms most likely to spawn:

• Hallway — the connective tissue. Always take it if drafted.
• Pantry / Kitchen — Step income. Best placed mid-spine for high-traffic crossings.
• Den — third Vault letter, top-right desk drawer.

Underground (Mine Layers)

Room 46 Path Overlay

Once you have all three Room 46 conditions met, the optimal path from the Atrium to the West Wing's far wall is short:

1. From the Atrium, move west through the central spine.
2. Cross 2–3 doors into the West Wing's middle column.
3. Take any door that leads to column 1 (the leftmost wall).
4. The Room 46 outline is on the wall of column 1, around row 3 from the bottom.
5. Use the Brass Key on the outline.

Mansion Map FAQ

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