As anyone who's ever tried to get a ticket for an event in Aldwych ghost station will know, poking around in the catacombs, tunnels and hidden rooms beneath the city is a surprisingly popular obsession. Look, then, to Museum of London's Festival of Archaeology this weekend (20 and 21 July), which opens up several rarely seen spaces.
Billingsgate Roman Bathhouse
An unremarkable office block at 101 Lower Thames Street conceals some of the best preserved Roman remains in the City. Archaeologists will be on hand to describe the remains of an ancient bathhouse. Free, just turn up, 11am-1pm and 2-4pm on both Saturday and Sunday.
Roman Fort Gate
A subterranean NCP car park next to the Museum of London contains a portal to lost Londinium. Step through the door and you'll find extensive remains of the old fort gate. Free, just turn up, 11am-1pm and 2-4pm on both Saturday and Sunday.
Spitalfields Charnel House
See the remains of a medieval bone store, discovered beside Spitalfields Market during the redevelopment. English Heritage experts will be on hand (not literally). Free, just turn up, 11am-5pm on Saturday
Get a peek inside the Museum's metal store and conservation labs, where you can examine metallic discoveries from the past 4,000 years. Tours at 10.15am, 12.15pm, 2.15pm and 4.15pm on both days. This one needs prebooking and costs a tenner.
Perhaps the prize ticket (we know how macabre you lot can be) is a visit to the Museum's bone store. It's full of skelingtons of long perished Londoners, and staffed by osteology curators willing to show you round. Tours at 10.30am, 12.30pm and 2.30pm (both days), and 4.30pm (Saturday only). This also needs prebooking and costs a tenner.
Other activities include an archaeology-themed play session for the under-7s, tours of the Museums archaeological archive in Islington (£3), and a talk about the Temple of Mithras. See the Museum of London website for further details, including how to book (where applicable).