There was a museum at one point in the story. These are some thumbnail explorations for it.
The museum had a big tree around. This are some explorations of the silhouette and relationship between the two
And there was a X-Ray scan at the museum, a security check to detect Non-Unicorns
Some very early exploration for architectural styles in the Unicorn forest (called Everfree at some point)
There also was a palace (later a museum, later a tea shop)
MLP A New Generation - Bridlewood
Some of the work I did for My Little Pony: A new generation a few years ago, in this case some of the designs for the Unicorn forest (it had so many names! UNT during production)