Grand Architect's tap ability doesn't target the creature: "Tap an untapped blue creature you control"
Permalink
Since you already have 8 fetchlands in your deck, you could replace Memnites with Hedron Crabs. I love the deck, good luck with it! :)
Try Overgrown Battlements instead of Wall of Frosts. They give mana and are cheaper to cast. And maybe few Khalni Gardens? I really like the deck, good luck with it! :)