Portals into New Worlds

The realms of imagination are vast and glorious, and some stories even have several worlds within them. Portals are often depicted as the mystical gateways used to move between them. Venturing through these magic portals can lead to journeys full of surprises. Dare to cross through the portal?

Add books you've read that feature a magical or technological portal where a primary character is transported through it into a world, dimension or time that's different from theirs.