This new feature helps you see how a given location has changed over time.
How to use it
To try it out, please start with the Place for the current HSBC building in Central.
On the right of the screen you'll see a new menu item 'Previously at this location', showing a single option, 'HSBC Headquarters Building (3rd generation)'. Click it, and you're taken to the Place for that building, along with associated notes and photos.
For this building, you'll see the 'Previously at this location' now links you to 'City Hall (first generation)'. Click that to see the Place for the old City Hall.
This screen is a bit different. There's no 'Previously at this location' option, because I don't know what, if anything, was there before the City Hall building!
Also note that the 'Later at this location' gives you two options: 'Old Bank of China Building', and 'HSBC Headquarters Building (3rd generation)'. It's because the old City Hall was demolished in two phases, with HSBC building on one part of the plot, and the Bank of China building on the other.
So it's a simple navigator that lets you look at a building, and move backwards and forwards in time to see how the area changed.
How it works
If you're a contributor, I need you to make a couple of changes so this will work.
First, when you create a new Place, you'll see there's a new field available, 'Previous place(s) at this location:'. If you can, please fill it in. This is the information that makes the timeline feature work.
The other change is in the way we think about Places. Initially, a Place meant a location, regardless of what was built on it. So we created Places like Mandarin Oriental Hotel, site of former Queen's Building.
But as we create more Places, we come across sites that have had three or four buildings on them. Using a single Place for all those buildings is going to get very clumsy, so in future we'll treat one Place as one building. If one site has had four buildings over time, then we'll create four Places.
Looking ahead
Later we'll also record the years that a building was built and demolished. That will allow a broader timeline, with finer detail. eg if you were looking at the year 1955, you could see which buildings were standing then, and which were built or demolished in that year.
And when I'm really in day-dream mode, I'm imagining taking a scanned image of say a 1911 street map of Central, and overlaying it with all the buildings that we know were standing in that year.
Questions, ideas and feedback welcome!
Regards, David