Selmburg is a castle city located on a mountainous island in the middle of the lake of the floor. While viewing the castle from the outside, a white granite surface with serene spires at its center can be seen. It has green foliage throughout the city and a lake surrounding it, making it extremely beautiful when the sun shines upon it.
Kirito comes to this floor trailing Asuna, having been invited for a dinner at her house with the S-rank Ragout Rabbit's Meat he had caught earlier. After finishing dinner, Kirito and Asuna talk about the real world and they discuss forming a party, which Kirito finally agrees to under pressure from Asuna. As Kirito didn't know how long he could stay at her house without being rude, he leaves for his house and meets her tomorrow to party with her.
Later, Kirito and Asuna go back to her house after a tragic incident within the guild. Kirito requests to stay at her house for the night, which she allows. While in bed, Kirito asks Asuna if they want to get married. Asuna smiles and says yes. The newlyweds go to buy a house on the 22nd Floor. At first, Asuna offered to sell her house, but Kirito goes against the idea, instead collecting all their rare items and selling them to Agil to collect the Cor needed for the new house.
When the game was cleared, Kirito and Asuna watched as Selmburg crumbled into the clouds along with the other floors.