The Sky Citadel is the eighth area of Sonic Boom: Rise of Lyric. It is a colossal and marvelous city from the Ancients, located high up in the skies above Bygone Island, held suspended amongst the clouds through mysterious technology. Virtually untouched by time, it is an archaeological marvel.
In the quest for the final Chaos Crystal, Team Sonic journeyed to the Sky Citadel to find the Sky Crystal. However, they were tricked by Lyric to relinquish their Crystals to him in exchange for Sonic's life. Not beaten though, Team Sonic pursued Lyric through the floating city as it collapse to stop his plans to destroy the world.
The Sky citadel is in its simplicity an enormous city of the Ancients located high up in the sky amidst the upper cloud layers. It is surrounded by nothing but clouds with a slightly violet tint and obscures any view of the earth's surface below, though the sky can still be spotted above.
The Sky Citadel is comprised solely by buildings suspended in the air by unspecified blue orbs on their bottoms. As such, the area is entirely devoid of any solid ground. The whole city is made of pale rock and its architecture heavily features pillars, overarching openings, curves and dome-shaped rooftops. Structures here include temple-like buildings, walls that are several stories tall, floating platforms, ring-shaped roofs and interwoven roads, most of which is held up by pillars suspended in the air. Adorning all the surfaces are golden rims and the Ancients' runes and markings. Additionally, floating around the city on their own are cylinder-shaped towers and immensely long and large arch bridges.
Though ancient, the Sky Citadel is in fairly good condition, with the only wear being cracks in the walls, some rubble and a few collapsed roads. Some towers show more extensive damage, with large vines growing out of crumbling walls.
A thousand years ago, the Ancients hid away the Sky Crystal, one of their own Chaos Crystals, away in the Sky Citadel so that Lyric would not be able to find it.
When Team Sonic tried to reach the Sky Citadel through a teleporter to get the Sky Crystal, only Knuckles and Amy got through it as it was only designed to take two. After journeying through the city, Sonic and Tails managed to reach them in the Tornado. Soon after, the team found the Sky Crystal, but as they claimed it, Destruction Troops surrounded them. Lyric appeared and explained that he let them find the Crystals so he could then take them from them. Sonic refused to hand them over, but Lyric threatened Tails, Knuckles, and Amy that if they did not, Sonic would die. Not wanting to risk Sonic's life, they relinquished the Crystals. As Amy demanded Lyric to keep his promise however, Lyric told her that he had a better idea and hed his robots shoot Sonic down with several large energy blasts.
As Lyric left with the Crystals, Tails, Knuckles, and Amy dug through the rubble, fearing the worst. To their relief, Sonic survived the onslaught, and the group took off to stop Lyric. With the Sky Citadel collapsing around them from Lyric's robot army, Team Sonic reached their only means of escaping: the Tornado. Though a chuck of rock broke the road as they got ready to leave, causing the Tornado to fall, Tails got the plane flying and team began heading towards Lyric's Lair to stop the villain once and for all.
- This level bears many similarities with Sky Sanctuary Zone from Sonic & Knuckles.
- When Team Sonic hand over all their Chaos Crystals to Lyric who then flies away with them, the Shock Crystal and the red crystal are not shown among them. Also, in the first scene where Lyric leave with the Crystals, he is shown having two Verdant Crystals.