Books like The Book of Skulls by Robert Silverberg

A covert scientific team ventures into the isolated Area X, a reclaimed landscape rife with anomalies and unknown life. As discoveries deepen, hidden motives and secrets threaten to unravel the expedition and alter humanity’s understanding of nature.

Nothing, in all it's entirety.

Inspector Tyador Borlú journeys from Besźel to Ul Qoma to investigate the murder of a woman, navigating two distinct cities that both share one physical space yet have separate identities.

A collection of Borges’ short stories that frequently employ the labyrinth as a literary device, probing philosophical and everyday aspects of human life.

Neal Stephenson explores World War II cryptography and 21st‑century data security through intertwined stories of a wartime code‑breaker, his grandson, and a secret mission to create a "data haven."

1965 science‑fiction novel set on a fully colonized Solar System, exploring reality, unreality, drugs and religious themes.

A classic tale of aliens in our midst, exploring human responses to superior beings.

In Robert Silverberg’s science‑fiction novel, a former colonial officer returns to the alien world of Belzagor to seek redemption for crimes against its two intelligent species, the Nildoror and Sulidoror, whose ritual of rebirth he disrupted.

Robert Silverberg’s Hugo‑winning novella "Nightwings" explores a world dominated by the mystical Avluela the Flier, whose scarlet and ebony wings guide a lone watcher to an ancient city, leaving the sky and space unguarded.

An adventurous journey through the galaxy, uncovering the truth behind a mysterious past and facing a terrifying adversary.

A story of two Church officers, a legendary alien guardian, and a young human warrior trying to stop a creature known as a Vom from destroying the universe.

A 1975 science fiction novel that brilliantly captures the dystopian world of pervasive surveillance and cybernetic advancements gone awry.

Charles Orsino is a young man who becomes entangled in the complex world of organized crime in a futuristic America ruled by the Syndicate and the Mob.

Ethan Fortune and Skua September, mismatched as they are, are thrown together on a frozen world and find themselves fighting for survival.

A romance that weaves two couples’ lives across a twenty‑five‑year divide, blending love with scientific inquiry.

The Illuminatus! trilogy is a groundbreaking series of science fiction novels that explore the interconnectedness of the universe.

Robert A. Heinlein’s 1961 Hugo‑winning science fiction classic follows Valentine Michael Smith, a human raised by Martians, as he reshapes Earth’s culture with his alien worldview.

"Secret societies have fundamentally shaped America's cultural and political landscapes. In ways that are expected but never explicit, the bonds made and lessons learned through the most elite of secret societies have helped make their members senators, governors, ambassadors, CIA directors, Supreme Court justices, and even presidents. At the apex of these institutions stands Yale University and its ancient six secret societies, with their modern--and even more private--"underground" rivals. Tracing a history that has intrigued and enthralled for centuries, winning the attention of such writers as Ernest Hemingway, William Faulkner and F. Scott Fitzgerald, Skulls and Keys recounts the founding and growth of Yale's storied societies as they set the courses for self-education, ambition, and assimilation that have served to define our modern age."--Jacket flap.

A machine that duplicates everything leads to societal collapse and moral dilemmas.

When the senior population director dies, assistant Roy Walton assumes the title Master of Life and Death, navigating a crowded Earth, hostile aliens, and a dangerous immortality serum to keep society from collapsing.

A 20th‑century man named Clay is thrown into a distant future where Earth is inhabited by evolved human species—Skimmers, Eaters, Awaiters, Breathers, Interceders, and Destroyers—prompting a journey of discovery and self‑reflection.