Watercolor Castle in an Underground City

An ancient castle carved from basalt sits in the heart of an underground city. Painted in soft watercolor washes with loose edges and visible paper texture. The castle features slender towers, arched gates, and a weathered stone bridge spanning a dark subterranean chasm. Surrounding caverns reveal a maze of market streets and tunnels lit by warm amber torches and pale blue bioluminescent fungi. Water drips down damp walls, pooling on mossy stones while crystal veins sparkle in the rock. The color palette blends muted blues, greens, and purples with warm gold highlights, creating a magical, dreamlike mood. The perspective is slightly elevated, with the underground river and a distant gate guiding the eye toward the castle.