Let's not dwell on fares, costs, crowds, delays and insufferable heat in summer. What's good about the dear old London Underground?

That map. If you don't love Harry Beck's perfect London Underground map, you're an uncultured barbarian. It's beautiful, functional and stylish. And it's not just the map that's beautiful design. The London Underground logo, font and general design work seen as standard is really classy. It's also really great to see stuff survive from the past: the coloured tile work at Covent Garden is beautiful (and coloured orange (I think) so passengers who can't read know what station they're at by the hue).

Number two. It's extraordinary that the Tube as we know it grew out of a selection of privately funded and speculative companies and lines built in the second half of the 19th century. We've bidden farewell to the Trafalgar Square stop and British Museum but when you have a long walk in a station from one line to the other, it's worth reflecting that the reason is (almost certainly) that the two lines were built decades apart or previously operated by different corporations that weren't organised centrally. Our Tube has evolved semi-organically since the 1860s: private chaos, nationalisation, part-denationalisation (or whatever) and much decay have taken their toll but it's still here and that's marvellous.

Three. Whether it's those classic uplighters on the escalators in Northern Line stations (think Kennington), the classic burgundy tiled station exteriors of Central London, majestic Art Deco stations (I'm thinking Chiswick Park) on the Piccadilly line or post-modern cathedrals on the Jubilee line (Westminster, Southwark, Canary Wharf, North Greenwich) some of the buildings are as pleasurable as any other architecture in London. Damn it, I even like the dreadful mosaics at Tottenham Court Road.

Four. I snogged a girl many years ago in the passport photo booth at Embankment and still have the strip of four different pics (somewhere) we took. Where is she now?

Five. Quirks. Inspector Sands. I like it when they call for Inspector Sands. St Johns's Wood is the only stop with none of the letters of mackerel in it. Cockfosters. Cockfosters is just funny. There's a Tardis outside Earl's Court. The track between Covent Garden and Leicester Square is only 260 metres long and a single ticket between the two is more expensive metre for metre than an old Concorde flight between London and New York… need I go on? What's not to love?

*I asked friends on Twitter to suggest blog topics. This one is for Josordoni.