The well of stars - Robert Reed

The Great Ship is home to a multitude of alien races and a near-immortal crew. They have toured the Milky Way for millennia, the best and the brightest from a thousand worlds, but the true purpose of the Ship has remained hidden. Now, time is running out. The huge spacecraft is heading for the dark, immense, region of space known as the Ink Well, and the only entity in the universe more vast and mysterious than the Great Ship is lying in wait ...

'THE WELL OF STARS is wonderful far-future SF of the best kind: imaginative, epic, mind-blowing, but anchored by a strong sense of character and a glorious cast of heroes and rogues. The Great Ship is surely one of the most audacious creations in recent SF.' ALASTAIR REYNOLDS