Block (The Curse of Fatal Death)

After the Doctor seemingly outsmarted the Master by, after the Master bribed the architect of Castle Tersurus to create the Spikes of Doom, travelling to a point further back in time to bribe the architect to build the Sofa of Reasonable Comfort, the Master revealed that he had anticipated this, and that he had travelled back in time and bribed the architect even earlier to drop a giant block on the Doctor and his companion, Emma's, heads. After the block landed, the Doctor and Emma walked out of a door on the side of the block, with the Doctor having travelled even further back, bribing the architect even earlier. (TV: The Curse of Fatal Death)