Rarity's small business before the war, located in Ponyville. Carousel Boutique was a clothes and dressmaking business, run solely by Rarity. She catered to clients far and wide, throughout Equestria, including places like Fillydelphia and Trottingham. The boutique, likely also served as her home in Ponyville.
After the apocalypse, the boutique was still standing. It was a frequent home to Raiders that lived in Ponyville. Littlepip took shelter inside Carousel Boutique after she emerged from Stable 2 and spent the night there, before leaving in the morning and killing the rest of the Raiders, infesting the Ponyville ruins.
The Boutique has also appeared in side stories
After investigating the fate of Stable 112's residents and killing a group of Raiders, Appletart Longshot left Ponyville when the GDCS Kodiak II crash landed. Appletart returned to Ponyville alongside the rescued Zyon and spent the night in Carousel Boutique, taking time to bathe and rest.
Appletart used the Boutique to scope out the wasteland outside and killed an infected Hoofington Raider from inside the Boutique, using This Machine.