A round lighthouse standing on a rocky island in the sea. A stone brick plinth sits on the island, and the tower rises 29 layers in five red and white bands. At the top are a wide gallery, a glass lantern room with a glowstone light inside, and a black conical roof. A small keeper's cottage with a red gable roof stands against the tower. 35 × 35 blocks, 47 layers, 3,419 blocks, 11 block types.
The tower is round, so it has no front; the cottage is in the top-right (north-east) of the pattern. The tower narrows as it rises — 13 across, then 11 from LAYER 15 and 9 from LAYER 29. The island is a ring of dark prismarine topped with a mix of stone, cobblestone and mossy cobblestone, with four boulders of the same stone scattered on top. The plan is meant to be built on water, so the bottom three island layers are open rings.
Layer by layer — island, plinth and cottage, five-band tower, gallery and lantern
LAYER 1–2 — rock rising from the sea. Two rings of dark prismarine, 35 and 33 across (226 and 212, 438 in all). The rings are two or three blocks thick and empty inside.
LAYER 3 — island edge. One more ring, one block in: 105 stone, 48 mossy cobblestone and 44 cobblestone, 197 in all.
LAYER 4 — island top. 214 stone, 154 cobblestone and 104 mossy cobblestone cover the island, leaving the tower's footprint open in the middle. The bottom row of the cottage walls (19 white concrete) starts on this layer too.
LAYER 5–6 — plinth and boulders. A thick stone brick ring fitting inside 17 × 17 (193 blocks: 85 and 108) makes the tower plinth. Four boulders of stone, cobblestone and mossy cobblestone go on the island — 134 blocks in all; the biggest, at the bottom (south) of the pattern (65 blocks), reaches LAYER 8.
LAYER 4–10 — keeper's cottage. A 7 × 5 house against the plinth, north-east of the tower. The walls are white concrete, four high on LAYER 4–7 (79 blocks), and the red concrete gable roof steps in to 5, 3 and 1 wide on LAYER 8, 9 and 10 (58 blocks). The single top row is the ridge.
LAYER 7–35 — the tower. Stack rings of white and red concrete. From the bottom the bands are white LAYER 7–12, red 13–18, white 19–24, red 25–30 and white 31–35 — six layers each, except the top white band with five. The tower goes from 13 across to 11 at LAYER 15 and 9 at LAYER 29, and it is hollow inside with no floors. The tower alone takes 716 white and 488 red concrete.
LAYER 36–37 — the gallery. A round 15 × 15 platform that sticks out three blocks on every side of the tower top: 140 stone bricks, with 112 black concrete laid over them.
LAYER 38–42 — lantern and light. Run a black concrete railing round the gallery edge (56 blocks, LAYER 38), and inside it raise a ring of glass 9 across, five layers high (168 glass). That leaves a walkway about two blocks wide between railing and glass. In the middle, a 3 × 3 glowstone column five layers high (45 blocks) rises from a base of 28 stone bricks on LAYER 38. LAYER 39–41 are identical, grouped as x3 in the pattern.
LAYER 43–47 — the roof. A black concrete cone that steps in from 9 to 7 to 5 across and then to a single block (94 blocks), capped with one quartz block on LAYER 47.
Gathering materials — mostly sand and cobblestone
Concrete, 1,603 is nearly half the build — 795 white, 546 red and 262 black. Each batch of 8 powder takes 4 sand, 4 gravel and 1 dye, so that is 100 white, 69 red and 33 black batches — 808 sand, 808 gravel, 100 white dye, 69 red dye and 33 black dye — set with water. White dye can be made from bone meal.
The cobblestone family comes to 1,164 — 376 stone, 361 stone bricks, 250 cobblestone and 177 mossy cobblestone. Stone is cobblestone smelted once, and a stonecutter turns 1 stone into 1 stone brick (a crafting table makes 4 from 4), so you need 737 stone. Mossy cobblestone is cobblestone plus one vine or moss block each. Mine 1,164 cobblestone and you have it all.
Glass, 168 is 168 sand smelted. With the 737 stone that is 905 smelts — 114 coal at 8 items per coal. Counting the concrete, the build takes 976 sand.
Dark prismarine, 438 is 8 prismarine shards + 1 ink sac each — 3,504 shards, an ocean monument's worth. It is only used on the bottom two island layers, so see the substitutes in the FAQ. Glowstone, 45 is 180 glowstone dust, and the single quartz block at the top is 4 nether quartz — if you would rather not visit the Nether for one block, white concrete works.
Tips
The three island stones do not need to match block for block. LAYER 3–4 and the four boulders are about half stone, with the rest split roughly 3 : 2 between cobblestone and mossy cobblestone — scatter them in about that mix and it looks the same.
The tower rings change shape slightly from layer to layer — the spots where the wall is two blocks thick move around, so copying one layer straight up goes wrong. Only the layers grouped as x2, x3 or x5 in the pattern are identical; look at the next drawing fresh whenever a group ends.
The gallery is three blocks wider than the tower on every side. Finish the tower to LAYER 35, stand on the top ring and work outward one block at a time.