emboldened : to instill with courage

Source;http://www.merriam-webster.com/dictionary/emboldened

Thus emboldened, I scrambled down a ladder as cars and trucks whizzed by my head, walked through a dirt trench and a doorway cut into a brick wall, and took a step back in time, into the arched tunnel.

The author was filled with courage and he decided that he will go down the ladder and into the tunnels of where Bob Diamond discovered.