Bridge across New College Lane
The bridge across the entrance to New College Lane is commonly known as the “Bridge of Sighs” (after the Ponte dei Sospiri in Venice, which joins two buildings over the Rio di Palazzo canal). The old part of Hertford College on the right was in Catte Street, while the address of the new part on the left was originally Broad Street East.
The two images below shows what the entrance to the lane looked like without the bridge.
1830s: This view (drawn by William Delamotte and engraved by Orlando Jewitt) was published in James Ingram’s Memorials of Oxford. On the left is a glimpse of the side of 28 Broad Street:

1880: Historic England: CC50/00298, with the view of New College's bell tower unobscured:
In 1901 Hertford College built a new block on the site of 28 Broad Street and 1, 2, 3, & 4 New College Lane (later extended right up to the Indian Institute.
The view below shows the same scene today, with Hertford's new building of 1901 on the left:

The bridge was designed by Thomas Graham Jackson and built in 1913 when Henry Boyd was Principal of Hertford College to join the older part of the college on the right to the new 1901 building on the left: hence the centre of the bridge facing Catte Street (shown below) is inscribed HENRICUS BOYD PRINCIPALIS in the panel on the left and AD 1913 in that on the right. Inside the bridge are two flights of stairs.

See also:
- Oxford Journal Illustrated, 31 December 1913, p. 16: Photograph of the new bridge over New College Lane joining the old part of Hertford College to the new wing
- Wikipedia: Bridge of Sighs, Oxford
- Wikipedia: Bridge of Sighs, Cambridge
- Wikipedia: The original Bridge of Sighs in Venice