Istanbul or Athens?

Athens has a real seaside. The Riviera runs south from Faliro through Glyfada to Vouliagmeni and Varkiza, linked to the centre by tram and bus. It has organised lidos with rocky free stretches between them, and the coves get clearer the farther south you go.

Istanbul lives beside the water but does not swim in it near the centre. Its beaches are the long sandy strands of Kilyos and Sile on the Black Sea, about an hour away and known for undertow, plus a few pebbly coves on the Princes' Islands. In Athens a swim fits into an ordinary sightseeing day. In Istanbul it means a dedicated outing.

Both cities eat at shared tables of small dishes, the Athenian taverna with ouzo and the Istanbul meyhane with rakı, but Istanbul has the greater range. It gathers cooking from all over Turkey, from Black Sea anchovies to south-eastern kebabs and Ottoman palace dishes. Its street food, from fish sandwiches by the Galata Bridge to stuffed mussels and kokoreç, could feed you for days on its own.

Athens answers with simple, generous cooking in Psyrri, Koukaki and Pangrati, and Greek wines such as assyrtiko and agiorgitiko belong on every table. The best grazing in Istanbul is in Kadikoy's market streets on the Asian shore, while in Athens the Varvakios market is the place to watch the city shop.

Both are among the world's great historic cities, and the difference is in era. Athens is the classical world: the Parthenon above every street, the Agora and Kerameikos along a pedestrian promenade, and the Acropolis Museum and National Archaeological Museum holding the finest ancient art. Beyond Plaka and Anafiotika, though, the modern city is mostly plain apartment blocks.

Istanbul layers Byzantium and the Ottomans. Hagia Sophia, the Blue Mosque and Topkapi stand side by side, with Sinan's Süleymaniye, the Chora mosaics and the Theodosian walls further out, and palaces and waterside mansions along the Bosphorus. The sights are more spread out, but the streets between them carry far more history.

Both cities go out late and keep going until dawn in summer, when the clubbing moves to the water: the coast towards Glyfada in Athens, the Bosphorus shore at Ortakoy and Kurucesme in Istanbul. Athens spreads its nights over more quarters, from Psyrri's rooftops facing the lit Acropolis to the clubs and gay scene of Gazi and student Exarchia, and drinking outdoors is normal everywhere.

Istanbul concentrates its nightlife in Beyoglu, Karakoy and Kadikoy, and heavy alcohol taxes make a night out costlier. Each has its own late-night tradition: in Athens the bouzouki club, where flowers are thrown on the dance floor, and in Istanbul the meyhane meal that turns into singing and dancing.

Athens has more proper country close by. Hymettus has pine trails on the city's edge, and Parnitha national park, an hour north, rises to 1,400m with fir forest and deer. The Saronic Gulf is good for sailing and windsurfing, though summer turns the hills brown and makes hiking a dawn activity.

Istanbul's outdoors is gentler and more urban. You walk the Bosphorus shore at Bebek and Rumeli Hisari, see tulips in Emirgan in April, follow shaded trails in Belgrad Forest and cycle on the Princes' Islands. No mountains are in reach, and the sheer size of the city makes leaving it slow.

This is one of the widest gaps between the two. From Athens, Sounion is an hour along the coast, and Delphi and the Argolid, with Mycenae, Epidaurus and Nafplio, are two hours or so away. Hydra, Poros and Aegina make real island outings by ferry from Piraeus.

Istanbul's easiest escapes are also by water: the Princes' Islands, and a cruise up the Bosphorus to Anadolu Kavagi and its Genoese castle. Bursa is the one strong town outing. Edirne and Iznik make long days, and Gallipoli and Troy need a night away.

Children are made welcome in both cities, and late family dinners are normal in each. Athens has the edge for small children on its calm Riviera beaches, and the planetarium and the park and lake at the Stavros Niarchos centre fill other days.

Istanbul makes up for it with cheap Bosphorus ferry rides, the ships, trains and submarine of the Rahmi M. Koç Museum, aquariums and Miniaturk. Both are hard work with a pushchair: in Athens it is the heat and broken pavements, in Istanbul the crowds, cobbled hills and long transfers.

Neither city needs a car, but they work in different ways. Athens is the more compact. Syntagma, Plaka, Monastiraki and the Acropolis lie within one walkable area served by a simple metro, which has antiquities on show in its stations. Narrow, blocked pavements and summer heat take the pleasure out of longer walks, though.

Istanbul is far bigger but holds together with one card for metro, tram, funiculars and ferries, and crossing between continents by ferry is a highlight in itself. Its weak points are rush-hour crush on the T1 tram past the main sights and taxis crawling through traffic.

Istanbul is the clear choice for shopping. The Grand Bazaar's hans and courtyards, the Spice Bazaar and the craft streets between them, where copper and textiles are still sold street by street, make a working market quarter where haggling is expected. Cukurcuma's antiques and the Kadikoy flea markets cover the second-hand side.

Athens is narrower in scope, with chain stores on Ermou, boutiques in Kolonaki and the weekend flea market around Avissynias Square. Its best buys are local and small: handmade leather sandals, mountain honey and herbs, and jewellery after ancient designs.

The costs are much alike, and in both cities you only travel cheaply if you live like a local. Athens keeps everyday spending low with souvlaki, bakeries, neighbourhood tavernas and cheap transport. Acropolis-view hotels in summer and site entry fees soon add up, though, so Koukaki and Pangrati make the thrifty bases.

In Istanbul, ferries, tea, simit and lokanta lunches cost very little. Hotels in Sultanahmet and Galata, high monument fees for foreigners and heavily taxed alcohol are what push the bill up. Staying in Kadikoy saves a great deal.

The two are closely matched, and in both most theatre is in the local language. Athens has the more spectacular summer stage, with opera and ancient drama in the Odeon of Herodes Atticus beneath the Acropolis and tragedy at Epidaurus. Its living tradition is rebetiko, played late in small tavernas.

Istanbul spreads its offer more evenly across the year and across styles. There is opera and ballet at the Ataturk Cultural Centre, summer jazz in historic courtyards and Sema ceremonies in old dervish lodges. Fasil musicians play in the meyhanes, and Beyoglu and Kadikoy have small venues for rock and Anatolian folk.

Athens offers little for a rest. Its old Ottoman bath in Plaka is now only a museum, and the centre is so hot and loud that finding calm usually means leaving it. The one place made for unwinding is Lake Vouliagmeni on the Riviera, a spring-fed pool under a limestone cliff where you can swim in mild water even in winter. For a real slow-down, the islands do it better than the capital.

Istanbul makes relaxation part of sightseeing, because its bathing tradition never stopped. You can spend an afternoon under one of Sinan's sixteenth-century domes a short walk from Hagia Sophia, or try a plainer neighbourhood bath used by local people. The city is every bit as noisy as Athens, but a slow ferry across the Bosphorus gives you a break that the Greek capital has no equivalent for.