The King of Elfland's Daughter by Lord Dunsany

In Erl that had sighed for magic there was indeed magic now. The pigeon-loft and old lumber-lofts over stables were all full of trolls, the ways were full of their antics, and lights bobbed up and down the street at night long after traffic was home. For the will-o'-the-wisps would go dancing along the gutters, and had made their homes round the soft edges of duck-ponds and in green-black patches of moss that grew upon oldest thatch. And nothing seemed the same in the old village.

And amongst all these magical folk the magical half of Orion's blood, that had slept while he went amongst earthly men, hearing mundane talk each day, stirred out of its sleep and awakened long-sleeping thoughts in his brain. And the elfin horns that he often heard blowing at evening blew with a meaning now, and blew stronger as though they were nearer.