WORD SPIRAL

Starting from 1, fill in the grid clockwise with four-letter words. The last letter of each word becomes the first letter of the next to reveal a type of building.

1. Nought 2. Rowing blades 3. Swing to and fro 4. Egg part 5. New Zealand bird 6. Unit of length 7. Brush or comb this 8. Peruse writing 9. Challenge 10. Water jug 11. Corrode 12. Mexican snack 13. Unlock 14. Bird's home 15. Upper-class person 16. Datum