A description of the St. Augustine summer solstice with a beautiful magenta sunset, featuring the Treasury Building across the Matanzas River, conjures a vivid and enchanting scene. Here's an imaginative depiction:

As the summer solstice unfolds in St. Augustine, the sky is ablaze with hues of magenta, casting a warm and ethereal glow over the ancient city. The sun, positioned at its zenith, bathes the landscape in a cascade of colors, creating a breathtaking canvas that heralds the longest day of the year.

The Matanzas River reflects the celestial spectacle, its waters mirroring the vibrant sky. Positioned majestically on the other side of the river, the Treasury Building stands as a stoic witness to the celestial drama. The architectural details of the building are subtly highlighted by the magenta twilight, adding an air of timeless elegance to the scene.

The atmosphere is imbued with a sense of tranquility and wonder as the city experiences the magical transition from day to night on this special solstice evening. Residents and visitors alike are treated to a mesmerizing display of nature's grandeur, with the Treasury Building serving as a silhouette against the radiant sky.