Besides the construction of Stonehenge, and of the castle for Uther Pendragon, he is said to have built Arthur's beautiful palace at Camelot.

He also devised sundry magic fountains, which are mentioned in other mediaeval romances.

One of these is referred to by Spenser in the "Faerie Queene," and another by Ariosto in his "Orlando Furioso." "This Spring was one of those four fountains rare, Of those in France produced by Merlin's sleight, Encompassed round about with marble fair, Shining and polished, and than milk more white.
There in the stones choice figures chiseled were, By that magician's god-like labour dight; Some voice was wanting, these you might have thought Were living, and with nerve and spirit fraught." ARIOSTO, _Orlando Furioso_ (Rose's tr.).
Merlin was also supposed to have made all kinds of magic objects, among which the poets often mention a cup.

This would, reveal whether the drinker had led a pure life, for it always overflowed when touched by polluted lips.

He was also the artificer of Arthur's armor, which no weapon could pierce, and of a magic mirror in which one could see whatever one wished.
"It Merlin was, which whylome did excel All living wightes in might of magicke spell: Both shield, and sword, and armour all he wrought For this young Prince, when first to armes he fell." SPENSER, _Faerie Queene_.
[Sidenote: Merlin and Vivian.] Merlin, in spite of all his knowledge and skill, yielded often to the entreaties of his fair mistress, Vivian, the Lady of the Lake.