The Hightower

"Wealthy, proud, and solitary, there have been Hightowers who wouldn't come down from their great lighthouse for decades. Its name, fittingly, the Hightower."

- Margaery Tyrell

The Hightower is a massive lighthouse located in Oldtown, the oldest city of Westeros. It serves as the seat of House Hightower, proud and wealthy bannermen of House Tyrell of Highgarden.

In the books
In the A Song of Ice and Fire novels, the Hightower is described as being 800 feet tall.