Sentence:  Going through the Imperial Gate in the wall , I entered the grounds of Topkapi Palace , home of the Sultans and nerve center of the vast Ottoman Empire , and walked along a road toward another gate in the distance , past the Church of St. Irene , completed by Constantine in 330 A. D. on my left , and then , just outside the second gate , I <WSD>saw</WSD> a spring with a tap in the wall on my right - the Executioner 's Spring , where he washed his hands and his sword after beheading his victims . 
Meaning of the word marked with <WSD> tags:  perceive by sight or have the power to perceive by sight