Robinson's Arch is the name of the ancient stairway which led to the Temple Mount in the time of the Second Temple. It allowed pedestrians on the lower street level to ascend to the Temple Mount, and is named for the archeologist who discovered its remains in the 19th century- Eduard Robinson. The only remaining part of the stairway today is the stone arch which held it, hence its name.
The Robinson's Arch is now part of the Jerusalem Archeological Garden, which is located just below the Temple Mount and to the right of the Mugrabi Bridge which now leads to the Dome of the Rock, on the southwestern corner of the Temple Mount. The stairway collapsed during the destruction of the ancient Temple in 70 CE, but researchers have determined its size and shape based on the findings on site.
The stairway's base was a large square structure made up of a number of floors. This building served pilgrims to the Temple, allowing them to bathe and purify themselves before entering the holy site. A complex pipe system led water to the bathhouses, and intricate mosaics testify that this was a luxurious building built to the highest standard of the time.
The steps from the street were lined with an elaborate railing and ended on top of the square structure, where a 90 degree turn led pilgrims to a wider staircase, which passed over the massive arch. This staircase ended directly in a double entryway which passed through the Western Wall and into the Temple Mount compound.
The giant arc covered the cobbled street below, and remains of the street and the arch's artwork have taught researchers that the arch was 15 meter long and 13 meters wide. The arch itself weighed approximately 1600 tons, and covered four street-level shops.
Constructing this arch and staircase required the best technology of the time, and the romans enlisted their finest engineers to develop a technique to build it. An intricate system of wooden scaffolding was used, and then covered by stone. Once the keystone was laid inside the arch, the wood was removed.
As the entire Second Temple was restored by King Herodes, researchers believe that he was also responsible for building Robinson's Arch. This took place in the latter part of the first century BCE. In and around the archeological park, researchers have discovered coins from the Herodian period which were made after his death. This testifies to the fact that construction of the arch took many dozens of years, and it was not completed in the time of the king that commissioned it.
The remains of the Robinson Archare visible to any visitor to the Jerusalem Archeological Park, which is directly adjacent to the Western Wall and the Temple Mount.