In the 17th century, French architect Thomas Gobert planned 12 churches whose forms spelled out the words LOVIS LE GRAND (where each letter is doubled mirrorwise, for symmetry):

In 1775 Johann David Steingruber designed a castle whose floor plan formed the initials of Prince Christian Carl Friedrich Alexander of Anspach:

And in 1774 Anton Glonner designed a Jesuit college based on the name of Christ (IHS, the first three letters of Jesus’ name in Greek):

The H contained the kitchen, the dining room, and the sacristy, and the S contained the schoolrooms.

(From Ulrich Conrads and Hans G. Sperlich, The Architecture of Fantasy, 1962.)