So I just got back from watching an episode of the Science Channel program Unearthed, a show focusing on archaeological discoveries. In the episode in question, the subject was on the Lighthouse of Alexandria, and one of the questions asked in the episode is how the lighthouse stood true in an earthquake hotspot for 1500 years. One theory was that the granite bricks were connected by a kind of mortar made from molten lead. A demonstration had been tested, and it turns out that a wall of granite bricks and molten lead mortar can withstand seismic shock without problem.
Now, obviously, lead is not a metal worth recommending, considering its toxic nature, but are there other metals or alloys that, when still molten, can be used to make mortar? And would it be practical to use them given today's technology?