Sky Island by L. Frank Baum — Read

All the Blueskins except a few soldiers had gone to bed and were sound asleep. A blue gloom hung over the city, which was scarcely relieved by a few bluish, wavering lights here and there, but Trot knew the general direction in which the palace lay, and she decided to go there first. She believed the Boolooroo would surely keep so important a prisoner as Cap'n Bill locked up in his own palace.

Once or twice the little girl lost her way, for the streets were very puzzling to one not accustomed to them, but finally she sighted the great palace and went up to the entrance. There she found a double guard posted. They were sitting on a bench outside the doorway, and both stood up as she approached.