White tulip-like flowers sheltered by large green leaves. What type of tree is this?, I wondered. I had once seen a tulip tree (Liriodendron tulipifera) and this one evidently a different type of tree.
After a while, I spotted the sign: Magnolia sieboldii subsp. sinensis. Chinese magnolia in common English.
One interesting detail: the tulip tree belongs to the magnolia family as well.